PhD, The University of Tokyo

Natural sciences, Semiconductors, optical and atomic physics

01 Oct. 2010
Institute for Laser Science, University of Electro-Communications, Associate Professor

Mar. 1999
The University of Tokyo, Graduate School, Division of Science, 物理学専攻

Mar. 1995
The University of Tokyo, Graduate School, Division of Science, 物理学専攻

Mar. 1993
The University of Tokyo, Faculty of Science, 物理学専攻

Apr. 1986 - Mar. 1989
神奈川県立横須賀高等学校

Apr. 2021 - Present
レーザー学会「次世代ファイバーレーザー技術」専門委員会幹事, レーザー学会, Society

Apr. 2015 - Present
レーザー学会研究委委員会委員, レーザー学会, Society

Oct. 2015 - Sep. 2023
Program Comittee, Asia Pacific Laser Symposium 2016-2023, Others

Apr. 2018 - Mar. 2021
レーザー学会「ファイバーレーザー技術」専門委員会委員, レーザー学会, Society

Dec. 2011 - Mar. 2018
レーザー学会「ファイバーレーザー技術」専門委員会副委員長, レーザー学会, Society

Jun. 2007 - Sep. 2008
次世代光・量子発生技術調査専門委員会, 電気学会, Society

2004 - 2005
光量子コヒーレンス制御技術調査専門委員会, 電気学会, Society

Apr. 2010
文部科学省
文部科学大臣表彰 若手科学者賞

May 2006
レーザー学会
第30回レーザー学会論文賞

May 1999
第23回レーザー研究奨励賞

Beam Combining Technologies for High Peak Power Fiber Lasers
Akira Shirakawa; Henrik Tȕnnermann
Lead, The Review of Laser Engineering, 51, 1, 12-16, Jan. 2023, Peer-reviwed, Invited
Scientific journal, Japanese

Kerr-lens mode-locked Yb:LuAG ceramic thin-disk laser
Shotaro Kitajima; Akira Shirakawa; Hideki Yagi; Takagimi Yanagitani
Optics Letters, The Optical Society, 46, 10, 2312-2312, 15 May 2021, Peer-reviwed
Scientific journal

Phase-locked and mode-locked multicore photonic crystal fiber laser with a saturable absorber
Tomonari Kawamura; Akira Shirakawa; Kazuya Saito
Optics Express, Optica Publishing Group, 29, 11, 17023-17028, May 2021, Peer-reviwed, Multicore photonic crystal fiber (MC-PCF) can scale the output power with the number of cores by spatial beam combining if the in-phase mode is selected. We demonstrated simultaneous realization of phase-locked and mode-locked laser using Yb-doped 7-core MC-PCF by a semiconductor saturable absorber placed in the near-field inside a resonator. High energy 333 nJ pulses were obtained directly from a mode-locked fiber laser oscillator at a 42.4 MHz repetition rate with an average power of 14.1 W at 24 W excitation. We observed the direct output pulse width of 52 ps assuming a sech(2) profile. However, it might be noise-like pulses because of no variation when we performed pulse compression. Single-pulse operation was achieved by increasing the bandwidth of the intracavity filter. In this case, 137 nJ, 42.4 MHz pulses were generated with a 5.8 W average power and the compressed output pulse width was 8.6 ps. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Scientific journal, English

Phase-locked and mode-locked multicore photonic crystal fiber laser with a saturable absorber
Tomonari Kawamura; Akira Shirakawa
Proc. SPIE, 11665, 116651N-1-116651N-6, Mar. 2021, Peer-reviwed
Scientific journal, English

Deep Reinforcement Learning for Tiled Aperture Beam Combining in a Simulated Environment
H. Tunnermann; A. Shirakawa
Journal of Physics: Photonics, 3, 1, 015004, Jan. 2021, Peer-reviwed
Scientific journal, English

可飽和吸収体による位相同期モード同期マルチコアフォトニック結晶ファイバーレーザー
川村朋稔; 白川晃
レーザー学会第511回研究会報告「ファイバーレーザー技術」, RTM-20, 19, Nov. 2020
Symposium, Japanese

Deep reinforcement learning for coherent beam combining applications
H. Tunnermann; A. Shirakawa
Optics Express, 27, 17, 24223-24230, Aug. 2019, Peer-reviwed
Scientific journal, English

Sub-100  fs pulse generation from a Kerr-lens mode-locked Yb:Lu2O3 ceramic thin-disk laser
S. Kitajima; A. Shirakawa; H. Yagi; T. Yanagitani
Optics Letters, 43, 21, 5451-5454, Nov. 2018, Peer-reviwed
Scientific journal, English

Kerr-Lens Mode-Locked Yb:Lu2O3 Ceramic Thin-Disk Laser
S. Kitajima; A. Shirakawa; H. Yagi; T. Yanagitani
Proc. of CLEO 2018, SF2N.5, May 2018, Peer-reviwed
International conference proceedings, English

Kerr-Lens Mode-Locked Yb:Lu2O3 Ceramic Thin-Disk Laser
S. Kitajima; A. Shirakawa; H. Yagi; T. Yanagitani
Proc. of CLEO 2018, SF2N.5, May 2018, Peer-reviwed
International conference proceedings, English

ファイバレーザの高出力化のためのコヒーレントビーム結合
白川晃
レーザー協会誌, 43, 1, 10-15, Apr. 2018, Invited
Scientific journal, Japanese

Probabilistic phase control for coherent beam combining
Henrik Tu¨nnermann; Akira Shirakawa
Optics InfoBase Conference Papers, OSA - The Optical Society, 2018, JTh2A.138, 2018, Peer-reviwed, Using probabilistic phase control, we realize coherent beam combining without using explicit modulation or polarization for error signal generation. Furthermore, the technique allows fusing multiple types of sensor data.
International conference proceedings, English

Delay line coherent pulse stacking
Henrik Tunnermann; Akira Shirakawa
OPTICS LETTERS, OPTICAL SOC AMER, 42, 23, 4829-4832, Dec. 2017, Peer-reviwed, Ultrafast fiber amplifiers are usually limited in terms of pulse energy and peak power due to fiber damage and non-linearities. On the other hand, fiber amplifiers are very energy efficient. To take advantage of this efficiency, but still scale the pulse energy, coherent combining and pulse stacking have become the method of choice. Here we show how to directly and symmetrically stack up the pulses from an oscillator chain, using delay lines and phase preshaping of a 48 MHz, 1.5 mu m master oscillator. This method avoids the need for high-power low-loss dumpers as in passive stack and dump cavities and, compared to divided pulse amplification (DPA), it eliminates the need for splitting pulses and pulse picking and, thus, optimally utilizes the available seed power. Furthermore, it avoids the asymmetrical gain of the pulse bursts, which typically limits the efficiency in DPA. (C) 2017 Optical Society of America
Scientific journal, English

Error signal generation for coherent combining using Baysian filters
Henrik Tünnermann; Akira Shirakawa
レーザー学会第511回研究会報告「ファイバーレーザー技術」, RTM-17, 38, Nov. 2017
Symposium, English

1120 nm high-power ytterbium-Raman fiber source
A. Shirakawa; Y. Michibata
Proc. of ICO-24, Tu1K-02, Aug. 2017, Peer-reviwed
International conference proceedings, English

Mode-locked Yb:Lu2O3 ceramic laser at two different wavelengths
S. Kitajima; T. Matsumoto; A. Shirakawa; H. Yagi; T. Yanagitani
Proc. of ICO-24, Th3C-06, Aug. 2017, Peer-reviwed
International conference proceedings, English

Conical refraction, for annular pumping of an efficient vortex Nd:YAG laser
Guiyun Li; Kegui Xia; Zhongyang Wang; Hao Shen; Akira Shirakawa; Ken-ichi Ueda; Jianlang Li
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 14, 7, 075001, Jul. 2017, Peer-reviwed, We presented a proof-of-concept investigation upon an end-pumped and vortex Nd:YAG laser. In this laser, for the first time, the conical refraction (CR) ring of a biaxial KGd(WO4)(2) crystal was used for annular pumping. Owing to nearly 100% conversion efficiency in forming the CR ring, the Nd: YAG laser was highly efficient and emitted LG(01)-mode vortex light with 177.5 mW beam power and 65% slope efficiency. This study showed the CR ring pumping would favor the production of a compact, simple and efficient vortex laser. It is expected that, in future, the CR ring pumping technique would also facilitate the high-power vortex solid-state laser where a long gain medium is required.
Scientific journal, English

Delay line coherent pulse stacking of a symmetric mode-locked pulse train
H. Tünnermann; A. Shirakawa
Proc. of CLEO-Europe/EQEC 2017, CJ-5.5 MON, Jun. 2017, Peer-reviwed
International conference proceedings, English

Femtosecond mode-locked Yb3+-doped CaF2-LaF3 ceramic laser
S. Kitajima; A. Shirakawa; K. Ueda; H. Ishizawa
Proc. of CLEO-Europe/EQEC 2017, CA-6.5 MON, Jun. 2017, Peer-reviwed
International conference proceedings, English

Mode analysis in phase-locked multi-core photonic crystal fiber laser by interference method
Y. Kurosu; H. Tünnermann; A. Shirakawa
Proc. of CLEO-Europe/EQEC 2017, CJ-P.3 MON, Jun. 2017, Peer-reviwed
International conference proceedings, English

Yb3+-doped CaF2-LaF3 ceramics laser
Shotaro Kitajima; Kentaro Yamakado; Akira Shirakawa; Ken-ichi Ueda; Yoshinobu Ezura; Hitoshi Ishizawa
OPTICS LETTERS, OPTICAL SOC AMER, 42, 9, 1724-1727, May 2017, Peer-reviwed, Highly transparent ceramic is an attractive gain medium for high-power lasers due to its high fracture toughness, homogeneity, and size scalability. Here we report the first Yb3+-doped CaF2-LaF3 ceramics laser. Codoping of La3+ ion can reduce the formation of Yb2+ ions and enhance the laser efficiency. In the laser experiment, the maximum output power of 4.36 W and the maximum slope efficiency of 69.5% were obtained with a 3% La, 2% Yb sample and a 2% La, 1% Yb sample, respectively. Due to the combined properties of Yb: CaF2 and a ceramic laser gain medium, Yb: CaF2-LaF3 ceramic is a promising gain medium for a high-power ultrashort pulse laser and amplifier. (C) 2017 Optical Society of America
Scientific journal, English

Combining efficiny in divied pulse amplification
E. Jo; K. Iwata; H. Tünnermann; A. Shirakawa
Proc. of ALPS '17, ALPS4-3, Apr. 2017, Peer-reviwed
International conference proceedings, English

SRS-suppressed photonic bandgap fiber amplifier using a laser diode as the seed source
D. Yagisawa; A. Shirakawa
Proc. of ALPS '17, ALPS4-2, Apr. 2017, Peer-reviwed
International conference proceedings, English

Sub-100 fs mode-locked Yb3+-doped CaF2 laser using single-walled carbon nanotube
N. Yokoshima; S. Kitajima; A. Shirakawa; S. Y. Choi; F. Rotermund
Proc. of ALPS '17, ALPS4-6, Apr. 2017, Peer-reviwed
International conference proceedings, English

Yb-doped CaF2-LaF3 ceramic laser
K. Yamakado; S. Kitajima; A. Shirakawa; K. Ueda; H. Ishizawa
Proc. of ALPS '17, ALPS6-6, Apr. 2017, Peer-reviwed
International conference proceedings, English

Observation of stimulated Raman scattering in polar tetragonal crystals of barium antimony tartrate trihydrate, Ba[Sb-2((+)C4H2O6)(2)]center dot 3H(2)O
Alexander A. Kaminskii; Hanjo Rhee; Hans J. Eichler; Oliver Lux; Ivan Nemec; Hitoki Yoneda; Akira Shirakawa; Petra Becker; Ladislav Bohaty
ANNALEN DER PHYSIK, WILEY-V C H VERLAG GMBH, 529, 4, 1600295, Apr. 2017, Peer-reviwed, The non-centrosymmetric polar tetragonal (P4(1)) barium antimony tartrate trihydrate, Ba[Sb-2((+)C4H2O6)(2)]center dot 3H(2)O, was found to be an attractive novel semi-organic crystal manifesting numerous chi((2)-) and chi((3)-)nonlinear optical interactions. In particular, with picosecond single- and dual-wavelength pumping SHG and THG via cascaded parametric four-wave processes were observed. High-order Stokes and anti-Stokes lasing related to two SRS-promoting vibration modes of the crystal, with omega(SRS1) approximate to 575 cm(-1) and omega(SRS2) approximate to 2940 cm(-1), takes place. Basing on a spontaneous Raman investigation an assignment of the two SRS-active vibration modes is discussed.
Scientific journal, English

CW performance and temperature observation of Yb: Lu2O3 ceramic thin-disk laser
Shotaro Kitajima; Hiroaki Nakao; Akira Shirakawa; Hideki Yagi; Takagimi Yanagitani
Optics InfoBase Conference Papers, OSA - The Optical Society, 2017, 2017, Peer-reviwed, CW Yb: Lu2O3 ceramic thin-disk laser with the maximum output power of 174 W was demonstrated. Slope efficiency was 54%. Disk temperature during lasing was observed and maximum temperature was 84.1 °C under 5.5 kW/cm2 pumping.
International conference proceedings, English

Coherent pulse stacking with delay lines
Henrik Tunnermann; Akira Shirakawa
FIBER LASERS XIV: TECHNOLOGY AND SYSTEMS, SPIE-INT SOC OPTICAL ENGINEERING, 10083, 10083-4, 2017, Peer-reviwed
International conference proceedings, English

Phase and combining efficiency in divided pulse amplification
Koji Iwata; Ei Jo; Henrik Tünnermann; Akira Shirakawa
Optics InfoBase Conference Papers, OSA - The Optical Society, 2017, ALPS4-3, 2017, Peer-reviwed, We show amplitude and phase retrieval of both pulses in a divided pulse amplification setup. We use this information to calculate the spectra on the combined and the rejected port and compare with our setup.
International conference proceedings, English

Single-walled carbon nanotube mode-locked Yb3+-doped CaF2 laser
Naoyuki Yokoshima; Shotaro Kitajima; Akira Shirakawa; Sun Young Choi; Fabian Rotermund
Optics InfoBase Conference Papers, OSA - The Optical Society, 2017, JTh2A.130, 2017, Peer-reviwed, We demonstrated SWCNT-assisted Kerr-lens mode-locked Yb:CaF2 laser. The pulse duration of 87 fs with 260-mW output power and the shortest pulse duration of 77 fs with 94-mW output power were obtained.
International conference proceedings, English

Phase and combining efficiency in divided pulse amplification
Koji Iwata; Ei Jo; Henrik Tünnermann; Akira Shirakawa
Optics InfoBase Conference Papers, OSA - The Optical Society, 2017, STh4K.6, 2017, Peer-reviwed, We show amplitude and phase retrieval of both pulses in a divided pulse amplification setup. We use this information to calculate the spectra on the combined and the rejected port and compare with our setup.
International conference proceedings, English

Coherent pulse stacking with delay lines
Henrik Tunnermann; Akira Shirakawa
FIBER LASERS XIV: TECHNOLOGY AND SYSTEMS, SPIE-INT SOC OPTICAL ENGINEERING, 10083, Oral 1-3H-3, 2017, Peer-reviwed
International conference proceedings, English

分割パルス増幅における位相と結合効率
岩田興治; チュナマン・ヘンリク; 白川晃
レーザー学会第496回研究会報告「ファイバーレーザー技術」, RTM-16, 31, Nov. 2016
Symposium, Japanese

Kerr-lens mode-locked Yb3+-doped Lu3Al5O12 ceramic laser
Shotaro Kitajima; Hiroaki Nakao; Akira Shirakawa; Hideki Yagi; Takagimi Yanagitani
OPTICS LETTERS, OPTICAL SOC AMER, 41, 19, 4570-4573, Oct. 2016, Peer-reviwed, Yb:LuAG is a promising gain medium for high-power lasers due to its high thermal conductivity and large emission cross section. Although narrowband gain media such as Yb: LuAG are not considered to be suitable for the generation of sub-100 fs pulses, we have achieved generation of 91 fs pulses with Yb: LuAG ceramic by the Kerr-lens mode-locking (KLM) technique. The obtained average power, pulse energy, and peak power were 1.64 W, 20.0 nJ, and 220 kW, respectively. These are, to the best of our knowledge, the first demonstration of KLM and the new records based on both Yb: LuAG ceramic and single crystal. (C) 2016 Optical Society of America
Scientific journal, English

Stimulated Raman scattering in natural crystals of fluorapatite, Ca-5(PO4)(3)F
Alexander A. Kaminskii; Ladislav Bohaty; Oliver Lux; Hanjo Rhee; Hans Joachim Eichler; Eugen Libowitzky; Reiner Kleinschrodt; Hitoki Yoneda; Akira Shirakawa; Petra Becker
LASER & PHOTONICS REVIEWS, WILEY-V C H VERLAG GMBH, 10, 5, 814-825, Sep. 2016, Peer-reviwed, Hexagonal Ca-5(PO4)(3)F, known as natural crystal fluorapatite and oldest host-crystal for Ln(3+)-lasant ions, is presented as a Raman-active material. High-order Raman-induced.(3)-nonlinear processes are discovered in natural crystals of fluorapatite under picosecond pumping at 1.064 mu m and 0.532 mu m wavelength. A multitude of Stokes and anti-Stokes components is generated in the ultraviolet, visible and near-infrared spectral region by stimulated Raman scattering (SRS) and Raman four-wave mixing (FWHM), resulting in a frequency comb with a width of 520 THz. The spectral lines are identified and attributed to the nu(1)(A(g)) vibration mode of the tetrahedral [PO4] units which is related to a Raman shift of omega(SRS) approximate to 965 cm(-1). The first Stokes steady-state Raman gain coefficient in the near-infrared spectral range is estimated to be > 0.38 cm.GW(-1). Finally, a short review of SRS-promoting vibration modes and observed.(3)-nonlinear interactions in all known SRS-active natural crystals (minerals) is given.
Scientific journal, English

Sub-100 fs Kerr-lens mode-locked Yb3+-doped Lu3Al5O12 ceramic laser
S. Kitajima; H. Nakao; A. Shirakawa; H. Yagi; T. Yanagitani
Proc. of 7th EPS-QEOD Europhoton Conference, SSL-6.6, Aug. 2016, Peer-reviwed
International conference proceedings, English

High-order Stokes and anti-Stokes Raman generation in monoisotopic CVD C-12-diamond
Alexander A. Kaminskii; Oliver Lux; Victor G. Ralchenko; Andrey P. Bolshakov; Hanjo Rhee; Hans J. Eichler; Akira Shirakawa; Hitoki Yoneda
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS, WILEY-V C H VERLAG GMBH, 10, 6, 471-474, Jun. 2016, Peer-reviwed, We determined, for the first time, the room temperature phonon energy related to the F-2g vibration mode (omega(SRS(12C)) similar to 1333.2 cm(-1)) in a mono-crystalline single-isotope CVD C-12-diamond crystal by means of stimulated Raman scattering (SRS) spectroscopy. Picosecond one-micron excitation using a Nd3+:Y3Al5O12-laser generates a nearly two-octave spanning SRS frequency comb (similar to 12000 cm(-1)) consisting of higher-order Stokes and anti-Stokes components. The spacing of the spectral lines was found to differ by Delta omega(SRS) similar to 0.9 cm(-1) from the comb spacing (omega(SRS)(natC) similar to 1332.3 cm(-1)) when pumping a conventional CVD diamond crystal with a natural composition of the two stable carbon isotopes C-12 (98.93%) and C-13 (1.07%). (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Scientific journal, English

Divided Pulse Amplification: Spectral Phase and Combining Efficiency
K. Iwata; H. Tuennermann; A. Shirakawa
Proc. of ALPS '16, ALPS6-2, May 2016, Peer-reviwed
International conference proceedings, English

Phase-locked 7-core multi-core photonic crystal fiber laser
Y. Kurosu; T. Kubouchi; H. Tuennermann; A. Shirakawa
Proc. of ALPS '16, ALPS6-3, May 2016, Peer-reviwed
International conference proceedings, English

Highly Efficient Yb3+-doped CaF2-LaF3 Ceramic Laser
Shotaro Kitajima; Yuki Higashi; Hiroaki Nakao; Akira Shirakawa; Ken-ichi Uedal; Yoshinobu Ezura; Hitoshi Ishizawa
2016 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE, JTh5A, 2016, Peer-reviwed, We prepared transparent Yb:CaF2-LaF3 ceramics with different combinations of doping concentrations of Yb3+ and La3+ and obtained CW laser operation with maximum output of 3.97 W. The maximum slope efficiency was as high as 73.1%.
International conference proceedings, English

Delay Line Coherent Pulse Stacking
Henrik Tunnermann; Akira Shirakawa
2016 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE, SM4Q.4, 2016, Peer-reviwed, We show a novel approach to coherent pulse stacking at 1.5 mu m. We use phase preshaping of a symmetric 47 MHz pulse train to combine pulses next to each other and in turn reducing the repetition rate to 23.5 MHz.
International conference proceedings, English

Highly Efficient Yb3+-doped CaF2-LaF3 Ceramic Laser
Shotaro Kitajima; Yuki Higashi; Hiroaki Nakao; Akira Shirakawa; Ken-ichi Uedal; Yoshinobu Ezura; Hitoshi Ishizawa
2016 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE, SM4R.2, 2016, Peer-reviwed, We prepared transparent Yb:CaF2-LaF3 ceramics with different combinations of doping concentrations of Yb3+ and La3+ and obtained CW laser operation with maximum output of 3.97 W. The maximum slope efficiency was as high as 73.1%.
International conference proceedings, English

可飽和吸収体を用いたQスイッチ位相同期マルコアファバーレーザー
久保内照雄; 黒須雄太; 佐藤慶吾; チュナマン・ヘンリク; 白川晃
レーザー学会第482回研究会報告「ファイバーレーザー技術」, RTM-15, 44, Nov. 2015
Symposium, Japanese

Single crystals of guanidinium zinc sulfate, [C(NH2)(3)](2)Zn(SO4)(2) - growth, structure, vibrational spectroscopy and stimulated Raman scattering
Ladislav Bohaty; Petra Becker; Eiken Haussuehl; Ivan Nemec; Oliver Lux; Hans Joachim Eichler; Hitoki Yoneda; Akira Shirakawa; Alexander A. Kaminskii
ZEITSCHRIFT FUR KRISTALLOGRAPHIE-CRYSTALLINE MATERIALS, WALTER DE GRUYTER GMBH, 230, 11, 639-649, Nov. 2015, Peer-reviwed, Large single crystals of the tetragonal (space group I (4) over bar 2d) guanidinium zinc sulfate, [C(NH2)(3)](2)Zn(SO4)(2), were grown and the crystal structure was redetermined. Vibrational spectra obtained by Raman and IR investigations are presented, together with an assignment of the observed vibration modes. Precise refractive index data in the wavelength range from 0.365 to 1.083 mu m are given. [C(NH2)(3)](2)Zn(SO4)(2) is introduced as a new stimulated Raman scattering (SRS)-active crystal with three SRS-active vibration modes with omega(SRS1) approximate to 985 cm(-1), omega(SRS2) approximate to 3390 cm(-1) and omega(SRS3) approximate to 1015 cm(-1). They allow for the generation of broadband nonlinear emission via chi((3))-(SRS and Raman-induced four wave mixing, RFWM) as well as cascaded chi((2))<->chi((3))-processes.
Scientific journal, English

Numerical analysis of fast saturable absorber mode-locked Yb3+ lasers under large modulation depth
Masaki Tokurakawa; Akira Shirakawa
OPTICS EXPRESS, OPTICAL SOC AMER, 23, 20, 26288-26298, Oct. 2015, Peer-reviwed, Numerical analysis of fast saturable absorber mode-locked Yb3+-doped solid state lasers is reported. The analysis includes a special case in which the spectral bandwidth of the short pulse is larger than the fluorescence bandwidth of the gain material. The relationship between the available shortest pulse duration and modulation depth for a standard bulk and thin disk laser geometries with several gain materials are shown. The characteristic phenomena observed in our previous Kerr-lens mode-locked laser experiments were reproduced in the simulation. (C) 2015 Optical Society of America
Scientific journal, English

Femtosecond mode-locked Nd3+-doped Ba(Zr,Mg,Ta)O-3 ceramic laser
Y. Higashi; H. Nakao; A. Shirakawa; K. Ueda; A. A. Kaminskii; S. Kuretake; Y. Kintaka; K. Murayama; N. Tanaka
OPTICS LETTERS, OPTICAL SOC AMER, 40, 16, 3818-3821, Aug. 2015, Peer-reviwed, We have demonstrated continuous wave (CW) laser operation and the first, to the best of our knowledge, sub-200 fs mode-locked laser operation of Nd3+-doped Ba(Zr,Mg,Ta)O-3 ceramic. Its disordered crystalline nature exhibits a broad gain bandwidth of 30 nm with a high-emission cross section. It also has higher thermal and mechanical properties than Nd:glass. In CW operation, a maximum output power of 1.5 W under 6.2 W of absorbed pump power was obtained. In mode-locked operation, a pulse duration of 196 fs with an average power of 60 mW was successfully achieved. The laser spectrum straddled both fluorescence peaks of A-site and B-site Nd3+ ions. (C) 2015 Optical Society of America
Scientific journal, English

Coupled multicore fibers in the high power regime: Impact of core size mismatch
H. Tünnermann; A. Shirakawa
Proc. of CLEO-PR 2015, 28G2-4, Aug. 2015, Peer-reviwed
International conference proceedings, English

Lithium silicate, LiAlSi4O10 (petalite)-a novel monoclinic SRS-active crystal
A. A. Kaminskii; E. Haussuehl; H. J. Eichler; J. Hanuza; M. Maczka; H. Yoneda; A. Shirakawa
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 12, 8, 085002, Aug. 2015, Peer-reviwed, The discovery of chi((3))-nonlinear lasing by stimulated Raman scattering (SRS) in natural monoclinic crystal of petalite, LiAlSi4O10, is reported. All recorded Stokes and anti-Stokes lasing sidebands under picosecond laser pumping in the visible are identified and attributed to the two occurring SRS-promoting phonon modes with omega(SRS1) approximate to 490 cm(-1) and omega(SRS2) approximate to 357 cm(-1). A short review of known SRS-active crystalline minerals and observed manifestations of their chi((2))- and chi((3))-nonlinear interactions is given as well.
Scientific journal, English

Sub-200 fs mode-locked Nd3+-doped Ba(Zr,Mg,Ta)O3 ceramic laser
Y. Higashi; A. Shirakawa; K. Ueda; A. A. Kaminskii; S. Kuretake; Y. Kintaka; K. Murayama; N. Tanaka
Proc. of CLEO/Europe 2015, CA-2.4, Jun. 2015, Peer-reviwed
International conference proceedings, English

Impact of different order photonic bandgap in spectral filtering photonic bandgap fiber amplifier
M. Chen; S. R. Petersen; C. B. Olausson; T. T. Alkeskjold; A. Shirakawa
Proc. of CLEO/Europe 2015, CJ-P.14, Jun. 2015, Peer-reviwed
International conference proceedings, English

Large-mode-area hybrid photonic crystal fiber amplifier at 1178 nm
Sidsel R. Petersen; Mingchen Chen; Akira Shirakawa; Christina B. Olausson; Thomas T. Alkeskjold; Jesper Laegsgaard
OPTICS LETTERS, OPTICAL SOC AMER, 40, 8, 1741-1744, Apr. 2015, Peer-reviwed, Amplification of 1178 nm light is demonstrated in a large-mode-area single-mode ytterbium-doped hybrid photonic crystal fiber, relying on distributed spectral filtering of spontaneous emission at shorter wavelengths. An output power of 53 W is achieved with 29 dB suppression of parasitic lasing. Further power scaling is limited by parasitic lasing. (C) 2015 Optical Society of America
Scientific journal, English

Kerr-lens mode-locked Yb3+-doped Lu3Al5O12 ceramic laser
S. Kitajima; H. Nakao; A. Shirakawa; H. Yagi; T. Yanagitani
Proc. of ALPS '15, ALPS10-2, Apr. 2015, Peer-reviwed
International conference proceedings, English

Impact of different order photonic bandgap in spectral filtering photonic bandgap fiber amplifier
M. Chen; S. R. Petersen; C. B. Olausson; T. T. Alkeskjold; A. Shirakawa
Proc. of ALPS '15, ALPS13-5, Apr. 2015, Peer-reviwed
International conference proceedings, English

Self-focusing in multicore fibers
Henrik Tuennermann; Akira Shirakawa
OPTICS EXPRESS, OPTICAL SOC AMER, 23, 3, 2436-2445, Feb. 2015, Peer-reviwed, Self-focusing is the ultimate power limit of single mode fiber amplifiers. As fiber technology is approaching this limit, ways to mitigate self-focusing are becoming more and more important. Here we show a theoretical analysis of this limitation in coupled multicore fibers. Significant scaling of the self-focusing limit is possible even for coupled multicore fibers if the out-of-phase mode is chosen. On the other hand the in-phase mode can - depending on the coupling strength - be prone to instabilities. (C) 2015 Optical Society of America
Scientific journal, English

87 W, narrow-linewidth, linearly-polarized 1178 nm photonic bandgap fiber amplifier
Mingchen Chen; Akira Shirakawa; Christina B. Olausson; Thomas T. Alkeskjold
OPTICS EXPRESS, OPTICAL SOC AMER, 23, 3, 3134-3141, Feb. 2015, Peer-reviwed, High-power narrow-linewidth photonic bandgap fiber amplifier was demonstrated. In order to suppress stimulated Brillouin scattering, the seed linewidth was broadened by applying a random phase noise with an electro-optical modulator. A factor of 15 in terms of Brillouin gain suppression can be theoretically expected. An 87 W linearly-polarized (11 dB PER) and narrow-linewidth (780 MHz FWHM) output was obtained. (C) 2015 Optical Society of America
Scientific journal, English

High-power single-frequency fiber MOPA at 1178 nm
M. Chen; A. Shirakawa; C. B. Olausson; T. T. Alkeskjold
Proc. of Photonics West/LASE 2015, 9344-8, Feb. 2015, Peer-reviwed
International conference proceedings, English

Spectral analysis of SRS suppression in photonic bandgap fibers
M. Karow; Y. Suzuki; H. Tünnermann; A. Shirakawa
Proc. of Photonics West/LASE 2015, 9344-20, Feb. 2015, Peer-reviwed
International conference proceedings, English

Impact of coupling strength on self-focusing in multicore fibers
H. Tünnermann; A. Shirakawa
Proc. of Photonics West/LASE 2015, 9344-22, Feb. 2015, Peer-reviwed
International conference proceedings, English

Zircon, ZrSiO4 - A novel SRS-active crystal
Alexander A. Kaminskii; Petra Becker; Hanjo Rhee; Oliver Lux; Hans J. Eichler; Reiner Kleinschrodt; Reinhard Rueckamp; Hitoki Yoneda; Akira Shirakawa; Ladislav Bohaty
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, WILEY-V C H VERLAG GMBH, 252, 2, 305-315, Feb. 2015, Peer-reviwed, The discovery of chi((3))-nonlinear lasing by stimulated Raman scattering (SRS) in natural crystals of zircon, ZrSiO4, is reported. All recorded Stokes and anti-Stokes Raman-induced lasing components are identified and attributed to the two occurring SRS-promoting phonon modes with omega(SRS1) approximate to 1008 cm(-1) and omega(SRS2) approximate to 356 cm(-1), which are related to the anti-symmetric stretching vibration B-1g(nu(3)) and the bending mode E-g(nu(4)), respectively, of the crystal with symmetry D-4h(19) = I4(1)/amd. The study indicates the high potential of ZrSiO4 as an effective SRS crystal.
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Crystals of ZrSiO4, as used for sample preparation, together with a sample for SRS measurement. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Scientific journal, English

Spectrally-Filtering Photonic Bandgap Fiber Lasers
Akira Shirakawa
2015 OPTO-ELECTRONICS AND COMMUNICATIONS CONFERENCE (OECC), IEEE, 2015, Peer-reviwed, Photonic bandgap fiber lasers are realizing new laser spectra and nonlinearity mitigation that a conventional fiber laser cannot by distributed spectral filtering. The recent our works will be reviewed and the future will be discussed.
International conference proceedings, English

Femtosecond mode-locked Nd3+-doped Ba(Zr,Mg,Ta)O3 ceramic laser
Y. Higashi; H. Nakao; A. Shirakawa; K. Ueda; A. A. Kaminskii; S. Kuretake; Y. Kintaka; K. Murayama; N. Tanaka
Optics Letters, OSA - The Optical Society, 40, 16, 3818-3821, 2015, Peer-reviwed, We have demonstrated continuous wave (CW) laser operation and the first, to the best of our knowledge, sub-200 fs mode locked laser operation of Nd3+-doped Ba(Zr
Mg
Ta)O3 ceramic. Its disordered crystalline nature exhibits a broad gain bandwidth of 30 nm with a high-emission cross section. It also has higher thermal and mechanical properties than Nd:glass. In CW operation, a maximum output power of 1.5 W under 6.2 W of absorbed pump power was obtained. In mode-locked operation, a pulse duration of 196 fs with an average power of 60 mW was successfully achieved. The laser spectrum straddled both fluorescence peaks of A-site and B-site Nd3+ ions.
Scientific journal, English

Femtosecond mode-locked Nd3+-doped Ba(Zr,Mg,Ta)O3 ceramic laser
Y. Higashi; H. Nakao; A. Shirakawa; K. Ueda; A. A. Kaminskii; S. Kuretake; Y. Kintaka; K. Murayama; N. Tanaka
Optics Letters, OSA - The Optical Society, 40, 16, 3818-3821, 2015, Peer-reviwed, We have demonstrated continuous wave (CW) laser operation and the first, to the best of our knowledge, sub-200 fs mode locked laser operation of Nd3+-doped Ba(Zr
Mg
Ta)O3 ceramic. Its disordered crystalline nature exhibits a broad gain bandwidth of 30 nm with a high-emission cross section. It also has higher thermal and mechanical properties than Nd:glass. In CW operation, a maximum output power of 1.5 W under 6.2 W of absorbed pump power was obtained. In mode-locked operation, a pulse duration of 196 fs with an average power of 60 mW was successfully achieved. The laser spectrum straddled both fluorescence peaks of A-site and B-site Nd3+ ions.
Scientific journal, English

Monoclinic beta-BaY2F8-a novel crystal simultaneously active for SRS and Ln(3+)-ion lasing
A. A. Kaminskii; O. Lux; J. Hanuza; H. Rhee; H. J. Eichler; J. Zhang; D. Tang; D. Shen; H. Yu; J. Wang; H. Yoneda; A. Shirakawa
LASER PHYSICS, IOP PUBLISHING LTD, 25, 1, 015801, Jan. 2015, Peer-reviwed, This paper presents the first investigation of stimulated Raman scattering (SRS) in the monoclinic fluoride crystal beta-BaY2F8, which is known as a promising host-material for trivalent lanthanide (Ln(3+)) lasant ions. Picosecond laser excitation in the visible and near-IR spectral range at room temperature revealed the manifestation of nine SRS-promoting phonon modes, which are related to Ag and Bg vibrations of the crystal. Besides multi-phonon Stokes and anti-Stokes generation, we observed cross-cascaded chi((3))<->chi((3)) processes involving different pairs of SRS-active phonons. A comparative estimation of the first Stokes steady-state Raman gain coefficients, both in the visible and near-IR region related to the most active SRS-phonon mode omega(SRS1) approximate to 208 cm(-1) of beta-BaY2F8, was also performed. Furthermore, a brief review of the pioneering papers on laser action of Ln(3+)-ions doped in beta-BaY2F8 single crystals and other known SRS-active fluoride crystals is given in tabular form.
Scientific journal, English

Stimulated Raman scattering spectroscopy of Y0.4Gd0.6VO4 crystals with partly disordered zircon-type structure-observation of new chi((3))-nonlinear optical interactions
A. A. Kaminskii; J. Zhang; O. Lux; H. Rhee; H. J. Eichler; D. V. Tang; H. H. Yu; H. J. Zhang; J. Wang; H. Yoneda; A. Shirakawa
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 11, 12, Dec. 2014, Peer-reviwed, This letter presents the results of stimulated Raman scattering (SRS) spectroscopy of tetragonal Y0.4Gd0.6VO4 vanadate crystals having a partly disordered zircon-type structure. Picosecond laser pumping revealed previously unexplored chi((3))-nonlinear interactions comprising the generation of an almost two-octave spanning Stokes and anti-Stokes frequency comb, self-third harmonic generation as well as cross-cascaded processes involving four different Raman-active modes. The recorded spectral lines have been assigned to the participating molecular vibrational modes of the (VO4)(3-) structural units of the studied crystal. In addition, this work provides a brief review of all known SRS-active tetragonal and monoclinic vanadates of the form REVO4 including their chi((3))-nonlinear properties and steady-state Raman gain coefficients for first Stokes generation.
Scientific journal, English

Monoclinic m-LaVO4-a novel high Raman gain SRS-active crystal
A. A. Kaminskii; H. Yu; H. Zhang; J. Wang; O. Lux; H. Rhee; H. J. Eichler; H. Yoneda; A. Shirakawa; J. Zhang; G. Tang
LASER PHYSICS, IOP PUBLISHING LTD, 24, 12, 125803, Dec. 2014, Peer-reviwed, Monoclinic m-LaVO4, having a monazite-type structure and being known as a host crystal for Nd3+-lasants, is an attractive chi((3))-nonlinear optical material for Raman laser converters. This paper presents the stimulated Raman scattering (SRS) spectroscopy of m-LaVO4 in the visible and near-IR spectral range using picosecond laser excitation. High-order SRS and Raman-induced four-wave parametric mixing processes result in an almost two-octave-wide Stokes and anti-Stokes frequency comb. All the measured spectral lines were assigned to the participating molecular vibration modes of the studied vanadate. Finally, an estimation of the steady-state Raman gain coefficient for first Stokes generation in near-IR was performed.
Scientific journal, English

Trigonal LaF3: a novel SRS-active crystal
A. A. Kaminskii; O. Lux; J. Hanuza; H. Rhee; H. J. Eichler; J. Zhang; D. Tang; D. Shen; H. Yoneda; A. Shirakawa
LASER PHYSICS, IOP PUBLISHING LTD, 24, 12, 125401, Dec. 2014, Peer-reviwed, Trigonal fluoride LaF3, widely known as a host crystal for Ln(3+)-lasants, was found to be an attractive many-phonon Raman material and a subject for the investigation of different chi((3))-nonlinear optical effects. We present the manifestation of photon-phonon interactions related to stimulated Raman scattering (SRS) and Raman-induced four-wave mixing (RFWM) processes, initiated by picosecond ex.itation at room temperature. Sesqui-octave-spanning Stokes and anti-Stokes frequency comb generation as well as many-step cascaded and cross-cascaded up-conversion chi((3))-nonlinear processes have been observed. The recorded spectral lines originated by SRS and RFWM are identified and attributed to the three observed SRS-promoting phonon modes. The lower limit of the steady-state Raman gain coefficient for near-IR first Stokes generation was estimated. Moreover, a brief review of known Ln(3+):LaF3 laser crystals and SRS-active fluorides is given.
Scientific journal, English

Orthorhombic YAIO(3) - a novel many-phonon SRS-active crystal
Alexander A. Kaminskii; Oliver Lux; Jerzy Hanuza; Hanjo Rhee; Hans Joachim Eichler; Hitoki Yoneda; Jian Zhang; Dingyuan Tang; Akira Shirakawa
LASER & PHOTONICS REVIEWS, WILEY-V C H VERLAG GMBH, 8, 6, 904-915, Nov. 2014, Peer-reviwed, In single crystals of orthorhombic YAlO3, widely known as a host-matrix for Ln(3+)-lasant ions, many-phonon stimulated Raman scattering interactions as well as different manifestations of cascaded and cross-cascaded nonlinear ((3)(3)) processes are initiated by picosecond laser pulses. The scientific and applicative potential of YAlO3 crystals is considerably expanded by the demonstration of its SRS properties. In particular, the studies revealed the manifestation of eight ((3))-active vibrational modes. The corresponding Stokes and anti-Stokes lines have been assigned and the steady-state Raman gain coefficients related to the strongest phonon mode have been estimated. In addition, a short review presents the stimulated emission channels of its Ln(3+)-ions together with some ((3))-nonlinear laser properties of crystals belonging to the binary Y2O3-Al2O3 system.
Scientific journal, English

High-power single-frequency fiber MOPA based on FRA and PBGF amplifier at 1178 nm
M. Chen; A. Shirakawa; C. B. Olausson; T. T. Alkeskjold
Proc. of Advanced Solid-State Lasers (ASSL) 2014, AM5A.32, Nov. 2014, Peer-reviwed
International conference proceedings, English

Self-focusing in multicore fibers
H. Tünnermann; A. Shirakawa
Proc. of Advanced Solid-State Lasers (ASSL) 2014, ATu2A.44, Nov. 2014, Peer-reviwed
International conference proceedings, English

Yb3+-doped ceramic thin-disk lasers of Lu-based oxides
Hiroaki Nakao; Tatsuya Inagaki; Akira Shirakawa; Ken-ichi Ueda; Hideki Yagi; Takagimi Yanagitani; Alexander A. Kaminskii; Birgit Weichelt; Katrin Wentsch; Marwan Abdou Ahmed; Thomas Graf
OPTICAL MATERIALS EXPRESS, OPTICAL SOC AMER, 4, 10, 2116-2121, Oct. 2014, Peer-reviwed, CW laser operations of thin-disk lasers with Lu-based oxide ceramics are reported. An output power of 166 W and a slope efficiency of 72.2% were obtained with an Yb:LuAG ceramic disk. We have also successfully demonstrated thin-disk lasers with Yb:Lu2O3 ceramics which were bonded by our soldering and gluing techniques. Slope efficiencies of 60.6% and 55.6% were obtained from a soldered disk and a glued disk, respectively. (C) 2014 Optical Society of America
Scientific journal, English

Multi-octave frequency comb generation by chi((3))-nonlinear optical processes in CVD diamond at low temperatures
O. Lux; V. G. Ralchenko; A. P. Bolshakov; V. I. Konov; G. V. Sharonov; A. Shirakawa; H. Yoneda; H. Rhee; H. J. Eichler; R. P. Mildren; A. A. Kaminskii
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 11, 8, 086101, Aug. 2014, Peer-reviwed, We study stimulated Raman scattering (SRS) and Raman four-wave mixing (RFWM) processes in chemical vapour deposition (CVD) diamond crystals. The strong interaction of picosecond laser pulses at 1.064 and 0.532 mu m wavelength with the dominant Raman-active F-2g mode results in a more than two-octave-spanning frequency comb, ranging from the UV to the NIR spectral region. In addition to spectroscopic analysis of the chi((3))-nonlinear emission at room temperature, comparative measurements have been carried out at cryogenic temperature of 10 K. The Raman shift and the Raman gain are found to change only weakly. Moreover, the potential of SRS frequency comb generation in CVD diamond for ultra-short pulse synthesis is discussed.
Scientific journal, English

Tetragonal SrGdGa3O7 and SrLaGa3O7-novel SRS-active crystals
A. A. Kaminskii; H. H. Yu; J. Y. Wang; Y. Y. Zhang; H. J. Zhang; O. Lux; H. Rhee; H. J. Eichler; J. Hanuza; H. Yoneda; A. Shirakawa
LASER PHYSICS, IOP PUBLISHING LTD, 24, 8, 085803, Aug. 2014, Peer-reviwed, We report on the first observation of stimulated Raman scattering (SRS) effects in tetragonal crystals of SrGdGa3O7 and SrLaGa3O7, known as host crystals for Ln(3+)-lasant ions. All recorded Raman-induced spectral lines were identified and attributed to the promoting chi((3))-vibrational modes of these gallates. Steady-state Raman gain coefficients for first Stokes generation were estimated. A short review of known simultaneous SRS-and Ln(3+)-laser active melilite-type crystals is given as well.
Scientific journal, English

Tetragonal LiLuF4 - A novel crystal simultaneously active for SRS- and Ln(3+)-lasing
A. A. Kaminskii; O. Lux; J. Hanuza; H. Rhee; H. J. Eichler; J. Zhang; H. Yoneda; A. Shirakawa
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, WILEY-V C H VERLAG GMBH, 251, 8, 1579-1589, Aug. 2014, Peer-reviwed, In this paper, the first investigation of stimulated Raman scattering (SRS) effects in the tetragonal crystal LiLuF4 is presented. It is known as a promising host-material for trivalent lasant lanthanides (Ln(3+)). We discovered its three "original" and one "combined" SRS-promoting modes at room temperature under picosecond laser excitation in the visible and near-IR spectral range. Apart from multi-phonon Stokes and anti-Stokes generation, we observed cross-cascaded chi((3)) <-> chi((3)) processes involving different pairs of SRS-active phonons. Furthermore, a comparative estimation of the stead-state Raman gain coefficient for first Stokes generation in LiLuF4 related to the most active SRS-phonon mode with omega(SRS1) approximate to 323 cm(-1) has been carried out for both the visible and near-IR. A brief review of the pioneering publications on laser action in Ln(3+)-ions of all known fluoride SRS-active single crystals is given in tabular form as well. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Scientific journal, English

Photonic bandgap fiber lasers and multicore fiber lasers for next generation high power lasers
A. Shirakawa; M. Chen; Y. Suzuki; K. Sato; X. Fan; H. Tünnermann; M. Karow; C. B. Olausson; S. R. Petersen; T. Alkeskjold; K. Saito
Proc. of Specialty Optical Fibers & Applications 2014, OSA, SoTu4B.2, Jul. 2014, Peer-reviwed
International conference proceedings, English

Demonstration of a Yb3+-doped Lu3Al5O12 ceramic thin-disk laser
Hiroaki Nakao; Akira Shirakawa; Ken-ichi Ueda; Hideki Yagi; Takagimi Yanagitani; Birgit Weichelt; Katrin Wentsch; Marwan Abdou Ahmed; Thomas Graf
OPTICS LETTERS, OPTICAL SOC AMER, 39, 10, 2884-2887, May 2014, Peer-reviwed, Yb:LuAG ceramic is very promising for thin-disk laser and amplifier architectures since it exhibits a higher thermal conductivity at high doping concentrations and a larger emission cross section than Yb:YAG. In this Letter, we present what we believe to be the first demonstration of a thin-disk laser based on Yb: LuAG ceramic. A maximum output power of 101 W with an optical efficiency of 56% and a slope efficiency of 64% was obtained with a multimode laser resonator. Fundamental-mode laser operation with near diffraction limited beam quality (M-2 approximate to 1.22) was also achieved. The fundamental-mode laser resonator showed the output power of 49 W, an optical efficiency of 31%, and a slope efficiency of 44%. A linearly polarized output beam was demonstrated in multimode operation using an intracavity Brewster window. The depolarization loss was measured to be as low as 0.15% per round trip. (C) 2014 Optical Society of America
Scientific journal, English

Low-temperature stimulated Raman scattering spectroscopy of tetragonal GdVO4 single crystals
A. A. Kaminskii; O. Lux; H. Rhee; A. Kaltenbach; H. J. Eichler; J. Zhang; D. Y. Tang; H. Yu; H. Zhang; J. Wang; H. Yoneda; K. Ueda; A. Shirakawa
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, WILEY-V C H VERLAG GMBH, 251, 5, 1045-1062, May 2014, Peer-reviwed, We report on the results of low-temperature stimulated Raman scattering (SRS)-spectroscopy of tetragonal GdVO4 single crystals. Measurements at T approximate to 9K and picosecond excitation in the visible and near-infrared range revealed new manifestations of ((3))-nonlinear photon-phonon interactions. Besides many-phonon Stokes and anti-Stokes octave spanning SRS generation we discovered a new fundamental ((3))-active phonon mode of the crystal. Furthermore, we received data on combined SRS-active vibrational modes. The lower limits of the steady-state Raman gain coefficients for first Stokes generation have been estimated together with the temperature dependence of these values in the range from T approximate to 9 and 273K. A short review of SRS-promoting vibrational modes and manifestations of ((3))-nonlinear interactions of all known SRS-active tetragonal rare-earth REVO4 vanadates is given as well.
Scientific journal, English

Yb3+-doped Lu2O3 ceramic thin-disk laser
H. Nakao; T. Inagaki; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani
Proc. of ALPS '14, ALPS2-8, Apr. 2014, Peer-reviwed
International conference proceedings, English

Phase-locked Q-switched multicore fiber laser with saturable absorber
K. Sato; T. Kubouchi; H.Yamada; A. Shirakawa
Proc. of ALPS '14, ALPS11-3, Apr. 2014, Peer-reviwed
International conference proceedings, English

Beryllium Silicate, Be2SiO4 (phenakite) - a Novel Trigonal SRS-Active Crystal
Alexander A. Kaminskii; Oliver Lux; Hanjo Rhee; Hans-Joachim Eichler; Hitoki Yoneda; Akita Shirakawa; Petra Becker; Ladislav Bohaty
LASER & PHOTONICS REVIEWS, WILEY-V C H VERLAG GMBH, 8, 2, 324-331, Mar. 2014, Peer-reviwed, In single crystals of the beryllium silicate Be2SiO4 with trigonal symmetry R (3) over bar, known also as the mineral phenakite, X-(3)-nonlinear lasing by stimulated Raman scattering (SRS) is investigated. All observed Stokes and anti-Stokes lasing components are identified and ascribed to a single SRS-promoting vibration mode with (SRS) approximate to 876 cm(-1). With picosecond single-wavelength pumping at one micrometer the generation of an octave-spanning Stokes and anti-Stokes comb is observed.
Scientific journal, English

Phase-locked, Q-switched multicore fiber laser by saturable absorber
A. Shirakawa; K.Sato; H.Yamada
Proc. of Photonics West/LASE 2014, 8961-8, Feb. 2014, Peer-reviwed
International conference proceedings, English

Nd-doped Ba(Zr,Mg,Ta)O-3 ceramics as laser materials
S. Kuretake; N. Tanaka; Y. Kintaka; K. Kageyama; H. Nakao; A. Shirakawa; K. Ueda; A. A. Kaminskii
OPTICAL MATERIALS, ELSEVIER SCIENCE BV, 36, 3, 645-649, Jan. 2014, Peer-reviwed, Transparent Nd3+-doped Ba(Zr,Mg,Ta)O-3 ceramics with disordered-type crystals were fabricated by adjusting the Ba(Zr,Mg,Ta)O-3 composition in order to substitute Nd dopants at different crystal sites. The XRD and XRFS analyses show that the substitution site of Nd ions changed as expected. In samples excited by a 805 nm laser diode, the shape of the fluorescence spectrum in the F-4(3/2) -> I-1(11/2) transition depends on the Ba(Zr,Mg,Ta)O-3 composition, and a maximum full width half maximum of 30.5 nm was obtained. In addition, the fluorescence efficiency also improved by adjusting the Ba(Zr,Mg,Ta)O-3 composition. (C) 2013 Elsevier B.V. All rights reserved.
Scientific journal, English

Single-frequency 1178 nm SDL/Yb-PBGF MOPA with an output power of 31 W
Tomi Leinonen; Mingchen Chen; Xinyan Fan; Emmi Kantola; Akira Shirakawa; Mircea Guina
FIBER LASERS XI: TECHNOLOGY, SYSTEMS, AND APPLICATIONS, SPIE-INT SOC OPTICAL ENGINEERING, 8961, 8961-4, 2014, Peer-reviwed, We report on the use of a Semiconductor Disk Laser (SDL) as a seed laser for an Ytterbium-Doped Photonic Bandgap Fiber (Yb-PBGF) amplifier in a Master-Oscillator Power-Amplifier (MOPA) configuration. The SDL comprised a GaInAs/GaAs/GaAsP gain chip, a 1-mm-thick etalon for mode selection, and a 3-mm-thick birefringent filter for wavelength tuning. The fiber amplifier consisted of an Yb-doped core surrounded by a structure of periodically arranged germanium rods with a pitch of 10.2 mu m, and to maintain the polarization, the fiber comprised two boron rods. The output of the MOPA-configuration was 31 W and the linewidth of the amplifier output was 149 +/- 31 kHz.
International conference proceedings, English

Single-frequency 1178 nm SDL/Yb-PBGF MOPA with an output power of 31 W
Tomi Leinonen; Mingchen Chen; Xinyan Fan; Emmi Kantola; Akira Shirakawa; Mircea Guina
FIBER LASERS XI: TECHNOLOGY, SYSTEMS, AND APPLICATIONS, SPIE-INT SOC OPTICAL ENGINEERING, 8961, 896105, 2014, Peer-reviwed, We report on the use of a Semiconductor Disk Laser (SDL) as a seed laser for an Ytterbium-Doped Photonic Bandgap Fiber (Yb-PBGF) amplifier in a Master-Oscillator Power-Amplifier (MOPA) configuration. The SDL comprised a GaInAs/GaAs/GaAsP gain chip, a 1-mm-thick etalon for mode selection, and a 3-mm-thick birefringent filter for wavelength tuning. The fiber amplifier consisted of an Yb-doped core surrounded by a structure of periodically arranged germanium rods with a pitch of 10.2 mu m, and to maintain the polarization, the fiber comprised two boron rods. The output of the MOPA-configuration was 31 W and the linewidth of the amplifier output was 149 +/- 31 kHz.
International conference proceedings, English

Phase-locked Multicore Fiber Lasers
Akira Shirakawa
2014 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE, STh4N.1, 2014, Arraying fiber lasers is being focused for power and energy scaling and multicore fibers can be a promising format. Phase locking in evanescently-coupled multicore fiber lasers by various in-phase mode selection methods is presented.
International conference proceedings, English

Yb3+-doped CaF2-LaF3 Ceramic Laser
A. Shirakawa; H. Nakao; Y. Higashi; K. Ueda; Y. Ezura; H. Ishizawa
Proc. of Advanced Solid-State Lasers (ASSL) 2013, JTh5A, Oct. 2013, Peer-reviwed
International conference proceedings, English

Efficient High Power Operation of Yb3+-doped Lu3Al5O12 ceramic thin-disk laser
H. Nakao; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; B. Weichelt; K. S. Wentsch; M. Abdou Ahmed; T. Graf
Proc. of Advanced Solid-State Lasers (ASSL) 2013, ATu3A.23, Oct. 2013, Peer-reviwed
International conference proceedings, English

Study of the thermo-optical constants of Yb doped Y2O 3, Lu2O3 and Sc2O3 ceramic materials
Ilya L. Snetkov; Dmitry E. Silin; Oleg V. Palashov; Efim A. Khazanov; Hideki Yagi; Takagimi Yanagitani; Hitoki Yoneda; Akira Shirakawa; Ken-Ichi Ueda; Alexander A. Kaminskii
Optics Express, Optical Society of American (OSA), 21, 18, 21254-21263, 09 Sep. 2013, Peer-reviwed, Thermally induced depolarization and thermal lens of three Konoshima Chemical Co. laser-ceramics samples Yb3+:Lu2O 3(CYb≈1.8 at.%), Yb3+:Y2O 3(CYb≈1.8 at.%), and Yb3+:Sc 2O3 (CYb≈2.5 at.%) were measured in experiment at different pump power. The results allowed us to estimate the thermal conductivity of the investigated ceramic samples and compare their thermo-optical properties. The thermo-optical constants P and Q and its sign measured for these materials at the first time. © 2013 Optical Society of America.
Scientific journal, English

Calcium dithionate tetrahydrate, CaS2O6 center dot 4H(2)O, a novel SRS-active crystal for octave-spanning many-phonon Stokes and anti-Stokes combs
A. A. Kaminskii; E. Haussuehl; S. Haussuehl; O. Lux; J. Hanuza; H. Rhee; A. Kaltenbach; H. J. Eichler; H. Yoneda; A. Shirakawa; K. Ueda
LASER PHYSICS, IOP PUBLISHING LTD, 23, 9, 095806, Sep. 2013, Peer-reviwed, This paper introduces a novel SRS-active crystal, hexagonal CaS2O6 center dot 4H(2)O, which was found to be an attractive Raman gain material and a suitable subject for the study of numerous nonlinear lasing effects. Under picosecond laser pumping in the UV, visible and near-IR spectral region we observed various manifestations of Raman induced nonlinear interactions. All registered Stokes and anti-Stokes components are identified and attributed to the participating chi((3))-promoting phonon modes. In the appendix, we present new data on the SRS properties of another dithionate, Na2S2O6 center dot 2H(2)O.
Scientific journal, English

Stimulated Raman scattering in monoclinic non-centrosymmetric guanylurea(1+) hydrogen phosphite (GUHP)
A. A. Kaminskii; P. Becker; H. Rhee; O. Lux; A. Kaltenbach; H. J. Eichler; A. Shirakawa; H. Yoneda; I. Nemec; M. Fridrichova; L. Bohaty
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, WILEY-V C H VERLAG GMBH, 250, 9, 1837-1856, Sep. 2013, Peer-reviwed, Monoclinic non-centrosymmetric guanylurea(1+) hydrogen phosphite (GUHP), (NH2)(2)CNHCO(NH2)H2PO3, was found to be an attractive SRS-active crystal manifesting numerous ((3))- and ((2))-nonlinear optical interactions. In particular, with picosecond single- and dual-wavelength pumping SHG, THG (via cascaded parametric four-wave processes), high-order Stokes and anti-Stokes lasing related to the ten SRS-active phonon modes of the crystal, octave spanning ((3))-lasing combs and cross-cascaded ((3)(3)) effects with different pairs of SRS-phonons were observed. The comparative estimation of the first Stokes steady-state Raman gain coefficients in the near-IR region allows the tentative conclusion, that their values can satisfy the practical requirements for the development of Raman laser converters. All recorded Raman-induced lasing lines were identified and attributed to the ((3))-active vibration modes of the crystal. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Scientific journal, English

Manifestations of nonlinear optical effects in a novel SRS-active Natural topaz, Al2(F1-x(OH)x)2SiO4: Many-phonon χ(3)-lasing, more than sesqui-octave Stokes and anti-Stokes multi-wavelength comb lasing
A. A. Kaminskii; O. Lux; H. Rhee; H. J. Eichler; H. Yoneda; A. Shirakawa; K. Ueda; R. Rückamp; L. Bohatý; P. Becker
Laser Physics Letters, 10, 7, 073001, Jul. 2013, Peer-reviwed, Natural crystals of topaz, Al2(F1-x(OH)x)2SiO4 were found to be an attractive Raman gain material and a subject for the investigation of different χ(3)-nonlinear optical effects. We present several manifestations of photon-phonon interactions related to SRS and RFWM processes initiated by picosecond excitations at room and cryogenic (≈9 K) temperature. Among them are octave-spanning Stokes and anti-Stokes generation in the visible and near-IR spectral range, combined SRS-active phonon modes, cross-cascaded up-conversion, χ(3)↔χ(3) lasing, as well as THG via self-sum frequency parametric generation. All recorded Raman-induced lasing lines are identified and attributed to the promoting χ(3)- vibration transitions. Based on the experimental data, theoretical simulations employing Fourier analysis are performed to demonstrate the potential of wide SRS frequency combs in terms of ultra-short pulse generation. © 2013 Astro Ltd.
Scientific journal, English

Monoclinic LaGaGe2O7:Nd3+ - A novel SRS- and SE-active crystal with high-order Stokes and anti-Stokes picosecond χ(3)-nonlinear lasing
A. A. Kaminskii; H. Rhee; O. Lux; A. Kaltenbach; H. J. Eichler; J. Hanuza; S. N. Bagayev; H. Yoneda; A. Shirakawa; K. Ueda
Laser Physics Letters, 10, 7, 075803, Jul. 2013, Peer-reviwed, Steady-state χ(3)-nonlinear generation in the host crystal LaGaGe2O7 for Nd3+(Ln3+)-lasants has been discovered. All the registered Stokes and anti-Stokes lasing sidebands are identified and attributed to its SRS-promoting phonon mode at ωSRS ≈ 882 cm -1. We have classified the studied germanate as a promising crystal for self-Raman laser converters. © 2013 Astro Ltd.
Scientific journal, English

Phosgenite, Pb2CO3Cl2 - a novel SRS-active crystal
Ladislav Bohatý; Petra Becker; Hanjo Rhee; André Kaltenbach; Hans J. Eichler; Hitoki Yoneda; Akira Shirakawa; Ken-Ichi Ueda; Alexander A. Kaminskii
Physica Status Solidi - Rapid Research Letters, 7, 6, 429-433, Jun. 2013, Peer-reviwed, Lead carbonate chloride, Pb2CO3Cl2, known as mineral phosgenite, is introduced as a novel SRS-active carbonate crystal with tetragonal symmetry. Under picosecond one-micron laser pumping Raman-induced χ(3)-nonlinear generation in the near-IR is observed. All recorded high-order Stokes and anti-Stokes sidebands are identified and attributed to two SRS-promoting vibration modes with ωSRS1 ≈ 1062 cm-1 and ωSRS2 ≈ 86 cm-1. Example of a natural crystal of phosgenite, Pb2CO3Cl2, from the locality of Monte Poni, Sardinia. © 2013 WILEY-VCH Verlag GmbH &
Co. KGaA, Weinheim.
Scientific journal, English

Investigation of the laser and,optical properties of Nd3+:Ba(Zr, Mg, Ta)O-3 ceramic, Nd3+(Na+):Ca2MgSi2O7 single crystal, and Yb3+:Lu3Al5O12. ceramic
Hiroaki Nakao; Akira Shirakawa; Ken-ichi Ueda; Alexander A. Kaminskii; Satoshi Kuretake; Nobuhiko Tanaka; Yuji Kintaka; Keisuke Kageyama; Hideki Yagi; Takagimi Yanagitani
OPTICAL MATERIALS, ELSEVIER SCIENCE BV, 35, 4, 700-703, Feb. 2013, Peer-reviwed, We report three new laser materials. Nd3+-doped Ba(Zr, Mg, Ta)O-3 ceramic indicates a broadband luminescence spectrum due to its disordered structure. By optimizing the manufacturing process and laser configuration, high output power and high slope efficiency operation was obtained. Nd3+(Na+:Ca2MgSi2O7 shows another type of spectral broadening caused by its structural modulation. In the input-output property, an anomalous behavior due to phase transition was observed. Yb3+:Lu3Al5O12 is one of the important laser materials for thin-disk laser because it indicates mild reduction of the thermal conductivity as an increase of concentration. The highly efficient CW laser operation is reported. (C) 2012 Elsevier B.V. All rights reserved.
Scientific journal, English

Experiments on Laguerre-Gaussian modes selection in ceramic lasers
Yu. Senatsky; J. -F. Bisson; J. Li; A. Shirakawa; M. Thirugnanasambandam; K. Ueda
PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 10, NO 6, WILEY-V C H VERLAG GMBH, 10, 6, 974-980, 2013, Peer-reviwed, A study on Laguerre-Gaussian (LG) modes selection in cw and pulsed Nd:YAG or Yb:YAG ceramic lasers pumped by diodes or an external laser source was carried out. Methods of scalar and vector LG modes selection from low to high orders, involving shaping of the pump profile, usage of intra-cavity lenses, uniaxial crystals and polarization selective mirrors, are considered. CCD camera images of beam profiles of hollow scalar LG(pm) modes (p-radial, m-azimuth indices) of record high-orders and Bessel-like multi-ring modes with highly directional propagation properties are presented. CW and pulsed ceramic lasers with radially or azimuthally polarized LG vector modes of low and high orders are also demonstrated. Applications of the developed laser schemes and LG beams are discussed. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
International conference proceedings, English

SRS in di-glycine nitrate (NH2CH2COOH)(2) center dot HNO3 crystals: Observation of high-gain many-phonon nonlinear interactions
Alexander A. Kaminskii; Oliver Lux; Eiken Haussuehl; Hanjo Rhee; Siegfried Haussuehl; Hans Joachim Eichler; Hitoki Yoneda; Akira Shirakawa; Ken-ichi Ueda; Jerzy Hanuza
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, WILEY-V C H VERLAG GMBH, 250, 1, 169-179, Jan. 2013, Peer-reviwed, Efficient high-gain many-phonon steady-state stimulated Raman scattering (SRS) was excited in the novel chi((3))-active organic crystal of di-glycine nitrate (DGN), (NH2CH2COOH)(2) center dot HNO3, at room temperature under picosecond laser pumping in the visible and near-IR regions. Besides high-order Stokes and anti-Stokes (comb) generation in this centrosymmetric crystal, several cascaded and cross-cascaded chi((3))<->chi((3)) nonlinear photon-phonon interactions were observed. The recorded Raman-induced lasing wavelengths were identified and attributed to the SRS-promoting optical vibration modes omega(SRS1)approximate to 1058 cm(-1), omega(SRS2)approximate to 2985 cm(-1), omega(SRS3)approximate to 895 cm(-1), and omega(SRS4)approximate to 3000 cm(-1). The measured large Raman frequency shifts (approximate to 3000 cm(-1)) and estimated moderately high steady-state Raman gain coefficients (g(ssR)(St1) >= 6.5 cm center dot GW(-1)) make this DGN crystal attractive for a number of new applications in modern laser physics and nonlinear optics.
Scientific journal, English

Thermo-optical constants of sesquioxide laser ceramics Yb3+:Ln(2)O(3) (Ln=Y,Lu,Sc)
I. L. Snetkov; D. E. Silin; O. V. Palashov; E. A. Khazanov; H. Yagi; T. Yanagitani; H. Yoneda; A. Shirakawa; K. Ueda; A. A. Kaminskii
PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 10, NO 6, WILEY-V C H VERLAG GMBH, 10, 6, 907-913, 2013, Peer-reviwed, Parasitic thermal effects (thermal depolarization and thermal lens) of three Konoshima Chemical Co. laser-ceramics samples Yb3+:Lu2O3 (C-Yb approximate to 1.8%), Yb3+:Y2O3 (C-Yb approximate to 1.8%), and Yb3+:Sc2O3 (C-Yb approximate to 2.5%) were measured in experiment at different pump power. The obtained results were used to calculate a number of thermo-optical constants, which showed that sesquioxide ceramics are significantly superior to the widely used yttrium aluminum garnet Yb3+:Y3Al5O12 (C-Yb approximate to 10%). (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
International conference proceedings, English

High power 1178 nm single-frequency MOPA based on OP-SDL and PBGF
Mingchen Chen; Xinyan Fan; Akira Shirakawa; Tomi Leinonen; Emmi Kantola; Mircea Guina; Christina B. Olausson; Jes Broeng
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest, MA1-3, 2013, Peer-reviwed, We report a high power single-frequency 1178 nm laser combining an optically-pumped semiconductor disk laser and an Yb-doped photonic bandgap fiber amplifier. An output power of 31 W with <
200 kHz linewidth without SBS was demonstrated. © 2013 IEEE.
International conference proceedings, English

98 W 1178 nm Yb-doped Solid-Core Photonic Bandgap Fiber Oscillator
Xinyan Fan; Mingchen Chen; Akira Shirakawa; Christina B. Olausson; Jes Broeng
2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS PACIFIC RIM (CLEO-PR), IEEE, TuA1-2, 2013, Peer-reviwed, A high power 1178nm Yb-doped photonic bandgap fiber laser is reported. A fiber Bragg grating and a Fresnel fiber end construct the resonator. 98W output power and 54% slope efficiency are achieved without parasitic lasing.
International conference proceedings, English

High- peak Power Pulse Amplification by SRS- suppressed Photonic Bandgap Fiber
Akira Shirakawa; Yuta Suzuki; Suguru Arisa; Mingchen Chen; C. B. Olausson; Jens K. Lyngso; Jes Broeng
2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS PACIFIC RIM (CLEO-PR), IEEE, TuA2-1, 2013, Peer-reviwed, We report Yb-doped photonic bandgap fiber amplifier generating 19 kW nanosecond pulses without stimulated Raman scattering by long-wavelength cut distributed filtering. Modulation instability due to the huge anomalous waveguide dispersion around the cutoff was observed.
International conference proceedings, English

Yb3+-doped Lu3Al5O12 ceramic thin-disk laser
Hiroaki Nakao; Akira Shirakawa; Ken-Ichi Ueda; Hideki Yagi; Takagimi Yanagitani; Birgit Weichelt; Katrin Wentsch; Marwan Abdou Ahmed; Thomas Graf
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest, ThA3-3, 2013, Peer-reviwed, First laser oscillation of Yb3+-doped Lu3Al 5O12 ceramic thin-disk laser is demonstrated. Maximum output power of 101 W was obtained from a 300-μm thick disk and 55% slope efficiency was obtained from a 150-μm thick disk. © 2013 IEEE.
International conference proceedings, English

98 W 1178 nm Yb-doped Solid-Core Photonic Bandgap Fiber Oscillator
Xinyan Fan; Mingchen Chen; Akira Shirakawa; Christina B. Olausson; Jes Broeng
2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS PACIFIC RIM (CLEO-PR), IEEE, 10, 10, 105101, 2013, Peer-reviwed, A high power 1178nm Yb-doped photonic bandgap fiber laser is reported. A fiber Bragg grating and a Fresnel fiber end construct the resonator. 98W output power and 54% slope efficiency are achieved without parasitic lasing.
International conference proceedings, English

Crystal-host Gd0.5Lu0.5VO4 for Ln(3+)-lasants: a new high-gain many-phonon chi((3))-active tetragonal vanadate-SRS spectroscopy and nonlinear-laser effects
A. A. Kaminskii; O. Lux; H. Rhee; H. J. Eichler; H. Yoneda; A. Shirakawa; K. Ueda; B. Zhao; J. Chen; J. Dong; J. Zhang
APPLIED PHYSICS B-LASERS AND OPTICS, SPRINGER, 109, 4, 649-658, Dec. 2012, Peer-reviwed, We found that tetragonal Gd0.5Lu0.5VO4-known as host-crystal for Ln(3+)-lasants-is an attractive optical material for Raman laser converters. We discovered and investigated its almost sesqui-octave Stokes and anti-Stokes lasing comb resulting from four SRS-promoting vibration modes in combination with cascaded and cross-cascaded many-phonon chi((3))-nonlinear interactions. Furthermore, estimations of the steady-state Raman gain coefficient have been performed.
Scientific journal, English

Single-frequency photonic bandgap fiber amplifier at 1178 nm
M. Chen; A. Shirakawa; X. Fan; K. Ueda; C. B. Olausson; J. K. Lyngsø J. Broeng
Opt. Express, 20, 19, 21044-21052, Aug. 2012, Peer-reviwed
Scientific journal, English

Mode-locked Yb3+-doped Lu3Al5O12 ceramic laser
H. Nakao; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani
Proc. of 5th EPS-QED Europhoton Conference 2012, TuP.10, Aug. 2012, Peer-reviwed
International conference proceedings, English

Single frequency amplification by ytterbium doped photonic bandgap fiber at 1178 nm
M. Chen; X. Fan; A. Shirakawa; K. Ueda; C. B. Olausson; J. K. Lyngsø J. Broeng
Proc. of 5th EPS-QED Europhoton Conference 2012, ThC.4, Aug. 2012, Peer-reviwed
International conference proceedings, English

CW and mode- locked operation of Yb3+-doped Lu3Al5O12 ceramic laser
Hiroaki Nakao; Akira Shirakawa; Ken-ichi Ueda; Hideki Yagi; Takagimi Yanagitani
OPTICS EXPRESS, OPTICAL SOC AMER, 20, 14, 15385-15391, Jul. 2012, Peer-reviwed, CW laser operation and first mode-locked laser operation of Yb:LuAG ceramic are reported. Efficient CW laser operation was obtained with maximum output power of 2.14 W and a 72% slope efficiency. Femtosecond mode-locked laser operation was achieved with pulse duration of 699 fs and a 200 mW average output power. (C) 2012 Optical Society of America
Scientific journal, English

High power Yb-doped photonic bandgap fiber oscillator at 1178 nm
Xinyan Fan; Meishin Chen; Akira Shirakawa; Ken-ichi Ueda; Christina B. Olausson; Jens K. Lyngso; Jes Broeng
OPTICS EXPRESS, OPTICAL SOC AMER, 20, 13, 14471-14476, Jun. 2012, Peer-reviwed, An ytterbium-doped solid-core photonic bandgap fiber oscillator in an all-fiber format is investigated for high power at an extreme long wavelength. The photonic bandgap fiber is spliced with two fiber Bragg gratings to compose the cavity. The sharp-cut bandpass distributed filtering effect of the photonic bandgap fibers efficiently suppresses amplified spontaneous emission in the conventional high-gain region. Fine adjustment of the short cut-off wavelength by coiling with tighter diameter is performed to suppress parasitic lasing. A record output power of 53.6 W with a slope efficiency of 53% at 1178 nm was demonstrated. (C)2012 Optical Society of America
Scientific journal, English

Continuous wave and mode-locked Yb3+:Y2O3 ceramic thin disk laser
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. A. Kaminskii; K. Beil; C. Krä nkel, G. Huber
Opt. Express, 20, 10, 10847-10852, Apr. 2012, Peer-reviwed
Scientific journal, English

High-order stimulated Raman scattering in tetragonal CaYAlO4 crystal-host for Ln3+-lasant ions
A. A. Kaminskii; X. Xu; O. Lux; H. Rhee; H. J. Eichler; J. Zhang; D. Zhou; A. Shirakawa; K. Ueda; J. Xu
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 9, 4, 306-311, Apr. 2012, Peer-reviwed, Multiple Stokes and anti-Stokes (3)-nonlinear generation in the tetragonal crystal of CaYAlO4 was observed at 300K and 9K under picosecond excitation in the visible spectral range. All the recorded Raman induced laser lines were identified and attributed to the SRS-promoting vibration mode of octahedral [AlO6]9 units of the crystal. (C) 2012 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA
Scientific journal, English

High-power single-frequency photonic bandgap fiber amplifier at 1178 nm
Meishin Chen; Akira Shirakawa; Yoshiaki Yamahara; Ken-ichi Ueda; Christina B. Olausson; Jens K. Lyngso; Jes Broeng
FIBER LASERS IX: TECHNOLOGY, SYSTEMS, AND APPLICATIONS, SPIE-INT SOC OPTICAL ENGINEERING, 8237, 82371H1-9, 2012, Peer-reviwed, 1178 nm single-frequency amplification by Yb-doped photonic bandgap fiber has been demonstrated. 24.6 W output was obtained without stimulated Brillouin scattering. 1.8 dB suppression of Brillouin gain by an acoustic antiguiding effect has been found in the low-index core antiresonant reflecting optical waveguide.
International conference proceedings, English

Continuous wave and mode-locked Yb3+:Y2O3 ceramic thin-disk laser
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; K. Beil; C. Krä nkel, K. Petermann; G. Huber
Proc. of Advanced Solid-State Photonics 2012, AM2A.4, Jan. 2012, Peer-reviwed
International conference proceedings, English

Efficient CW laser operation of Yb:LuAG ceramic laser
Hiroaki Nakao; Akira Shirakawa; Ken-ichi Ueda; Hideki Yagi; Takagimi Yanagitani
2012 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE, CM2D.4, 2012, Peer-reviwed, Laser-diode pumped Yb3+-doped LuAG ceramic laser is reported. Maximum 2.14 W output power and 72% slope efficiency were obtained. Higher thermal conductivity and higher emission cross-section than Yb:YAG will be suitable for thin-disk laser.
International conference proceedings, English

53.6 W, 1178 nm Yb-doped Photonic Bandgap Fiber Oscillator
Xinyan Fan; Meishin Chen; Akira Shirakawa; Ken-ichi Ueda; Christina B. Olausson; Jes Broeng
2012 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE, CM2N.5, 2012, Peer-reviwed, We report an 1178nm fiber oscillator using Yb-doped solid-core photonic bandgap fiber in an all-fiber format. 53.6W output power is achieved with 53% slope efficiency. ASE and parasitic lasing in high-gain wavelength is effectively suppressed.
International conference proceedings, English

New manifestations of chi((3))-nonlinear laser interactions in tetragonal LuVO4 and YbVO4 crystals attractive for SRS-converters and self-Raman lasers
A. A. Kaminskii; O. Lux; H. Rhee; H. J. Eichler; K. Ueda; H. Yoneda; A. Shirakawa; B. Zhao; J. Chen; J. Dong; J. Zhang
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 9, 12, 879-887, 2012, Peer-reviwed, We present several previously unexplored chi((3)) nonlinear laser effects under picosecond excitation in LuVO4 and YbVO4. Among them high-order Stokes and anti-Stokes generation related to discovered SRS-promoting vibration modes, with the manifestations of cross-cascaded chi((3)) <-> chi((3)) lasing processes involving new SRS-active phonons. All recorded spectral components of many-phonon chi((3))-nonlinear generation were identified and attributed to the vibrations of the (VO4)(3-) structural units of the studied vanadates. (C) 2012 by Astro, Ltd.
Scientific journal, English

Many-phonon stimulated Raman scattering and related cascaded and cross-cascaded ?(3)-nonlinear optical effects in melilite-type crystal Ca2ZnSi2O7
A. A. Kaminskii; H. Rhee; O. Lux; H. J. Eichler; L. Bohaty; P. Becker; J. Liebertz; K. Ueda; A. Shirakawa; V. V. Koltashev; J. Hanuza; J. Dong; D. B. Stavrovskii
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 8, 12, 859-874, Dec. 2011, Peer-reviwed, Different nonlinear optical interactions in a novel SRS-active non-centrosymmetric tetragonal crystal Ca2ZnSi2O7 were investigated at room and cryogenic (9 K) temperature under picosecond laser pumping. In addition to measuring octave-spanning Stokes and anti-Stokes combs we observed several cascaded and cross-cascaded ?(3) ? ?(3) effects involving several SRS-active phonons. All recorded Raman-induced lasing lines in the visible and near-IR range are identified and attributed to the SRS-promoting vibration transitions. A brief review of SRS- and Nd3+-doped laser-active melilite-type crystals is given as well. ((c) 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) ((c) 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
Scientific journal, English

Lutetium-aluminum garnet laser ceramics
M. Sh. Akchurin; R. V. Gainutdinov; I. I. Kupenko; Kh. Yagi; K. Ueda; A. Shirakava; A. A. Kaminskii
DOKLADY PHYSICS, MAIK NAUKA/INTERPERIODICA/SPRINGER, 56, 12, 589-592, Dec. 2011, Peer-reviwed
Scientific journal, English

CW one-micron (F-4(3/2)-I-4(11/2)) laser oscillation of Nd3+ ions in the melilite-type crystal Ca2MgSi2O7:Nd3+(Na+) at its incommensurate-commensurate phase transition
A. A. Kaminskii; H. Nakao; A. Shirakawa; K. Ueda; J. Liebertz; P. Becker; L. Bohaty
APPLIED PHYSICS B-LASERS AND OPTICS, SPRINGER, 103, 3, 629-635, Jun. 2011, Peer-reviwed, The spectroscopic and stimulated-emission (F-4(3/2)-> I-4(11/2)) properties of the novel melilite-type laser crystal Ca2MgSi2O7:Nd3+(Na+) were studied in a temperature range that covers its incommensurate-commensurate (ICa dagger"N) phase transition. The phase transition temperatures of both undoped Ca2MgSi2O7 and the doped crystal were ascertained at 346.6 K (undoped) and 341.3 K (doped) by means of differential scanning calorimetry (DSC). The temperature-dependent spectroscopic and laser experiments showed a significant decrease in CW output power and a strong distortion of the generated lasing beam in the region of the phase transition. The observed crystal field disorder of Nd3+ lasants in Ca2MgSi2O7:Nd3+(Na+) is dominantly due to occupation of the position of Ca2+ by cations of different valency, while the influence of incommensurability is of minor importance.
Scientific journal, English

Stimulated Raman scattering in "garnet" Lu3Al5O12 ceramics - a novel host-materiel for Ln- and TM-lasant ions
A. A. Kaminskii; H. Rhee; O. Lux; H. J. Eichler; S. N. Bagayev; H. Yagi; K. Ueda; A. Shirakawa; J. Dong
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 8, 6, 458-464, Jun. 2011, Peer-reviwed, In this paper are present results of the first investigation of stimulated Raman scattering (SRS) in the "garnet" Lu3Al5O12 crystalline ceramics, which is promising host-material for activator lasants. With picoseconds laser excitation at 0.53207 mu m wavelength was observed and analyzed highorder Stokes and anti-Stokes generation related to two. (3)promoting vibration modes (approximate to 792 and approximate to 375 cm(-1)) of this novel SRS-active oxide material. A brief review of the pioneering papers on lasers based on Lu3Al5O12:Ln(3+) single crystals and known SRS-active crystalline "garnet" materials is given in tabular form as well.
Scientific journal, English

Manifestations of new chi((3))- and chi((2))-nonlinear optical interactions and chi((2))-properties of orthorhombic bis(guanidinium) zirconium bis(nitrilotriacetate) hydrate, [C(NH2)(3)](2)Zr[N(CH2COO)(3)](2)center dot H2O crystal
Alexander A. Kaminskii; Lkhamsuren Bayarjargal; Eiken Haussuehl; Nicole Mueller; Siegfried Haussuehl; Hans J. Eichler; Hanjo Rhee; Ken-ichi Ueda; Akira Shirakawa; Georg A. Reider
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE, WILEY-BLACKWELL, 208, 3, 695-709, Mar. 2011, Peer-reviwed, Using single- and dual-wavelength coherent collinear pico-second pumping we observed in semi-organic heterodesmic orthorhombic [C(NH2)(3)](2)Zr[N(CH2COO)(3)](2)center dot H2O manifestations of several new chi((3))- and chi((2))-nonlinear optical effects, among them self-frequency doubling, "Cherenkov''-type second harmonic generation (SHG), cascaded self-frequency tripling and self-sum-frequency generation, as well as more than two-octave Stokes and anti-Stokes generation under one-micron excitation. All newly recorded nonlinear optical status solidi physica frequency components were identified and attributed to stimulated Raman scattering (SRS) promoting modes of the crystal. All three tensor components of the second order nonlinear optical susceptibility tensor (SHG tensor) were determined at the wavelength 1.064 mu m using the Maker fringe technique. The maximal value of the SHG tensor is 0.6 pm V-1. SHG phase matching directions of type-I/II and effective nonlinear susceptibilities are given for 0.7-1.4 mu m fundamental wavelengths. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Scientific journal, English

Multi-ring modes generation in Yb:YAG ceramic laser
Manasadevi P. Thirugnanasambandam; Yuri Senatsky; Akira Shirakawa; Ken-ichi Ueda
OPTICAL MATERIALS, ELSEVIER SCIENCE BV, 33, 5, 675-678, Mar. 2011, Peer-reviwed, A short-focus glass lens with strong spherical aberration was used for mode selection in the cw LD-end-pumped Yb:YAG ceramic laser. Sequence of low to very high order Laguerre-Gaussian (LG(pl)) modes with different combinations of radial, p and azimuthal, l indices (p <= 10, l <= 28), with output beam diameters 2-13 mm and power up to 30 mW was obtained. Peaked and hollow multi-ring beams with near-diffraction free propagation of the central minimum or maximum over 40 m distance from the laser resonator were observed. Mechanisms of mode selection and possible applications of the proposed laser scheme are considered. (C) 2010 Elsevier B.V. All rights reserved.
Scientific journal, English

Broadband-gain Nd3+-doped Ba(Zr, Mg, Ta)O-3 ceramic lasers for ultrashort pulse generation
H. Kurokawa; A. Shirakawa; M. Tokurakawa; K. Ueda; S. Kuretake; N. Tanaka; Y. Kintaka; K. Kageyama; H. Takagi; A. A. Kaminskii
OPTICAL MATERIALS, ELSEVIER SCIENCE BV, 33, 5, 667-669, Mar. 2011, Peer-reviwed, We report Nd3+-doped Ba(Zr, Mg, Ta)O-3 ceramic lasers. The fluorescence of the ceramics shows characteristic broadband spectra due to the disordered crystalline system and can be tailored by the composition adjustment. The continuous-wave laser operations as well as the first mode-locked laser operation are presented. (C) 2010 Elsevier B.V. All rights reserved.
Scientific journal, English

Ultrashort pulse generation from diode pumped mode-locked Yb3+:sesquioxide single crystal lasers
M. Tokurakawa; A. Shirakawa; K. Ueda; R. Peters; S. T. Fredrich-Thornton; K. Petermann; G. Huber
OPTICS EXPRESS, OPTICAL SOC AMER, 19, 4, 2904-2909, Feb. 2011, Peer-reviwed, We present diode pumped SESAM supported Kerr-lens mode locked laser operation based on Yb3+:Sc2O3 and Yb3+:Lu2O3 single crystals. Pulses as short as 71 fs with an average power of 1.09 W were obtained from an Yb3+:Lu2O3 single crystal. Yb3+:Sc2O3 delivered pulses as short as 81 fs with an average power of 840 mW. The mode locked laser operation was stable for longer than 2 hours. (C) 2011 Optical Society of America
Scientific journal, English

Single-Frequency Photonic Bandgap Fiber Amplification
Akira Shirakawa; Meishin Chen; Yoshiaki Yamahara; Ken-ichi Ueda; Christina B. Olausson; Jens K. Lyngso; Jes Broeng
2011 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE, CThU6, 2011, Peer-reviwed, Single-frequency operation in an ytterbium-doped photonic bandgap fiber amplifier is presented for the first time. 16 W, 1178 nm narrow linewidth radiation, free from both amplified spontaneous emission and stimulated Brillouin scattering, was obtained.
International conference proceedings, English

Na,Nd co-doped Ca2MgSi2O7 laser
Hiroaki Nakao; Akira Shirakawa; Ken-Ichi Ueda; Ladislav Bohaty; Petra Becker; Alexander A. Kaminskii
2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference, CLEO EUROPE/EQEC 2011, CA.P.17, 2011, Peer-reviwed, Broadband gain media for laser-diode (LD) pumped mode-locked laser have been widely studied. kermanite (Ca2MgSi2O7) is one of the melilite-type crystal which has a two-dimensionally incommensurate structural modulation. Ca1.96Nd0.02Na 0.02MgSi2O7 is the åkermanite doped with Nd3+ ions and co-doped with Na+ ions for charge compensation. Due to the restriction of ion sizes, it is expected the Ca 2+ ions are substituted by the Nd3+ ions and the Na + ions. The basic structure is shown in Fig. 1. The coordination number of the Ca-O is basically 8, but the size misfit between the Ca 2+ ions and the Mg2+ ions causes different coordination numbers of 6 and 7[1]. This is considered to be the origin of the structural modulation, but above 358K, the modulation disappears. Thus, åkermanite has the phase transition. The phase with the modulation was called incommensurate phase (ICphase) and the phase without the modulation was called normal phase (N-phase). In the IC-phase, broadening of the luminescence spectrum due to the modulation is expected. In addition, disordered location of Nd 3+ ions and Na+ ions also exists. This makes åkermanite disordered crystal and further spectral broadening is expected. Hence åkermanite is expected to be suitable for ultlashort pulse laser. © 2011 IEEE.
International conference proceedings, English

Q-switched multicore photonic crystal fiber laser phase-locked by end-seal technique
Akira Shirakawa; Hidenori Yamada; Michio Matsumoto; Masaki Tokurakawa; Ken-Ichi Ueda
2011 Int. Quantum Electron. Conf., IQEC 2011 and Conf. Lasers and Electro-Optics, CLEO Pacific Rim 2011 Incorporating the Australasian Conf. Optics, Lasers and Spectroscopy and the Australian Conf., 359-360, 2011, Peer-reviwed, Q-switched and phase-locked Yb-doped multicore fiber laser is reported. The monolithic in-phase mode selection at the output fiber end realizes clean single-lobe beam profile and high slope efficiency of 62% with 280μJ, 100ns pulses. © 2011 IEEE.
International conference proceedings, English

Single-Frequency Photonic Bandgap Fiber Amplification
Akira Shirakawa; Meishin Chen; Yoshiaki Yamahara; Ken-ichi Ueda; Christina B. Olausson; Jens K. Lyngso; Jes Broeng
2011 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE, AT1A.5, 2011, Peer-reviwed, Single-frequency operation in an ytterbium-doped photonic bandgap fiber amplifier is presented for the first time. 16 W, 1178 nm narrow linewidth radiation, free from both amplified spontaneous emission and stimulated Brillouin scattering, was obtained.
International conference proceedings, English

Single-Frequency Photonic Bandgap Fiber Amplification
Akira Shirakawa; Meishin Chen; Yoshiaki Yamahara; Ken-ichi Ueda; Christina B. Olausson; Jens K. Lyngso; Jes Broeng
2011 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE, 20, 19, 21044-21052, 2011, Peer-reviwed, Single-frequency operation in an ytterbium-doped photonic bandgap fiber amplifier is presented for the first time. 16 W, 1178 nm narrow linewidth radiation, free from both amplified spontaneous emission and stimulated Brillouin scattering, was obtained.
International conference proceedings, English

Stimulated emission (F-4(3/2) -> I-4(11/2) channel) with LD and Xe-flashlamp pumping of tetragonal, incommensurately modulated Ca2MgSi2O7:Nd3+(Na+) - a new disordered laser crystal
A. A. Kaminskii; H. Nakao; L. Bohaty; P. Becker; J. Liebertz; R. Kleinschrodt; K. Ueda; A. Shirakawa
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 7, 12, 876-883, Dec. 2010, Peer-reviwed, Non-centrosymmetric tetragonal crystal Ca2MgSi2O7:Nd3+(Na+) with incommensurately modulated melilite-type structure is presented as a new laser crystal. By LD and Xe-flashlamp pumping its CW and free-running pulsed stimulated emission of the F-4(3/2) -> I-4(11/2) generation channel of Nd3+ lasant ions was excited.
[GRAPHICS]
The single exponential decay-time plot of the metastable F-4(3/2) (initial laser) state of Nd3+ ions in a Ca2MgSi2O7 crystal together with approximate to 10 mu s excitation pulses (C) 2010 by Astro Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA
Scientific journal, English

New oxide ceramics {YGd2}[Sc-2](Al2Ga)O-12 with a partially disordered "garnet" structure as a matrix for the Ln(3+) laser activator ions: Some physical properties
M. Sh. Akchurin; R. V. Gainutdinov; I. I. Kupenko; A. V. Taranov; E. N. Hazanov; H. Yagi; K. Ueda; A. Shirakawa; M. Tokurakawa; A. A. Kaminskii
DOKLADY PHYSICS, MAIK NAUKA/INTERPERIODICA/SPRINGER, 55, 11, 537-540, Nov. 2010, Peer-reviwed
Scientific journal, English

More than two-octaves span of the Stokes and anti-Stokes picosecond lasing comb in orthorhombic natural single crystals of celestine, SrSO4
A. A. Kaminskii; L. Bohati; P. Becker; R. Kleinschrodt; H. J. Eichler; H. Rhee; K. Ueda; A. Shirakawa; V. Koltashev
Laser Physics Letters, 7, 10, 743-751, Oct. 2010, Peer-reviwed, Efficient room-temperature Stokes and anti-Stokes χ(3)-nonlinear picosecond generation, which spans more than two octaves (≈23012 cm-1) has been observed in a natural crystal of orthorhombic SrSO4 (celestine). All recorded lasing lines in the visible and near-IR regions are identified and attributed to its SRS-promoting vibration mode ωSRS ≈999 cm-1. © 2010 by Astro Ltd..
Scientific journal, English

High power ytterbium fiber lasers at extremely long wavelengths by photonic bandgap fiber technology
A. Shirakawa; C. B. Olausson; H. Maruyama; K. Ueda; J. K. Lyngsø J. Broeng
Optical Fiber Technology, 16, 6, 449-457, Oct. 2010, Peer-reviwed
Scientific journal, English

167 W, power scalable ytterbium-doped photonic bandgap fiber amplifier at 1178nm
C. B. Olausson; A. Shirakawa; M. Chen; J. K. Lyngso; J. Broeng; K. P. Hansen; A. Bjarklev; K. Ueda
OPTICS EXPRESS, OPTICAL SOC AMER, 18, 16, 16345-16352, Aug. 2010, Peer-reviwed, An ytterbium-doped photonic bandgap fiber amplifier operating at the long wavelength edge of the ytterbium gain band is investigated for high power amplification. The spectral filtering effect of the photonic bandgap efficiently suppresses amplified spontaneous emission at the conventional ytterbium gain wavelengths and thus enables high power amplification at 1178 nm. A record output power of 167 W, a slope efficiency of 61% and 15 dB saturated gain at 1178 nm have been demonstrated using the ytterbium-doped photonic bandgap fiber. (C) 2010 Optical Society of America
Scientific journal, English

Talbot共振器によるマルチコアファイバーレーザーのin-phaseモード選択励振
小林哲也; 白川晃; 植田憲一
レーザー研究, The Laser Society of Japan, 38, 2, 136-140, Feb. 2010, Peer-reviwed, We report on in-phase mode selection among the supermodes of an ytterbium-doped 19-core fi ber by a
Scientific journal, Japanese

Estimation of gain bandwidth limitation of short pulse duration based on competition of gain saturation
M. Tokurakawa; A. Shirakawa; K. Ueda
Proc. of Advanced Solid-State Photonics 2010, AMB16, Feb. 2010, Peer-reviwed
International conference proceedings, English

Power-scalable photonic bandgap fiber sources with 167 W, 1178 nm and 14.5 W, 589 nm radiations
A. Shirakawa; C. B. Olausson; M. Chen; K. Ueda; J. K. Lyngsø J. Broeng
Proc. of Advanced Solid-State Photonics 2010, APDP6, Feb. 2010, Peer-reviwed
International conference proceedings, English

Power-scalable long-wavelength Yb-doped photonic bandgap fiber sources
Christina B. Olausson; Akira Shirakawa; Hiroki Maurayama; Ken-ichi Ueda; Jens K. Lyngso; Jes Broeng
FIBER LASERS VII: TECHNOLOGY, SYSTEMS, AND APPLICATIONS, SPIE-INT SOC OPTICAL ENGINEERING, 7580, 758013, 2010, Peer-reviwed, Ytterbium-doped photonic-bandgap fiber sources operating at the long-wavelength edge of the ytterbium gain band are being investigated for high power amplification. Artificial shaping of the gain spectrum by the characteristic distributed filtering effect of the photonic bandgap enables power scaling free of amplified spontaneous emission. As high as 167 W power and 16 dB saturated gain at 1178 nm have been demonstrated. Single-pass frequency doubling to 14.5W 589nm light was also demonstrated with 34% conversion efficiency.
International conference proceedings, English

Continuous-wave and mode-locked lasers on the base of partially disordered crystalline Yb3+:{YGd2}[Sc2](Al2Ga)O12 ceramics
M. Tokurakawa; H. Kurokawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. A. Kaminskii
Opt. Express, 18, 2, 4390-4395, Jan. 2010, Peer-reviwed
Scientific journal, English

Diode-pumped mode-locked Nd3+-doped Ba(Zr,Mg,Ta)O-3 ceramic laser
H. Kurokawa; M. Tokurakawa; A. Shirakawa; K. Ueda; A. A. Kaminskii; S. Kuretake; N. Tanaka; Y. Kintaka; K. Kageyama
2010 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (QELS), IEEE, CMNN4, 2010, Peer-reviwed, Nd3+-doped Ba(Zr,Mg,Ta)O-3 ceramic laser is reported. The broadband fluorescence profile can be tailored by the "disordered" perovskite structure and is suitable for ultrashort pulse lasers. Mode-locked laser operation was demonstrated for the first time. (C) 2010 Optical Society of America
International conference proceedings, English

Photodarkening and Photobleaching of Yb-doped Fibers by Laser Diodes
Noriyuki Inoue; Akira Shirakawa; Ken-ichi Ueda
2010 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (QELS), IEEE, CMGG5, 2010, Peer-reviwed, Photodarkening and photobleaching of Yb-doped germanosilicate and aluminosilicate fibers have been studied. We show violet laser diodes (407nm) can efficiently bleach photodarkening even with low-intensity cladding-irradiation. Coirradiation of pumping and bleaching lights was also investigated. (C)2010 Optical Society of America
International conference proceedings, English

167 W, 1178 nm Ytterbium-Doped Photonic Bandgap Fiber Amplifier with Power Scalability
Christina B. Olausson; Akira Shirakawa; Meishin Chen; Jens K. Lyngso; Jes Broeng; Kim P. Hansen; Anders Bjarklev; Ken-ichi Ueda
2010 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (QELS), IEEE, CTuC2, 2010, Peer-reviwed, We have generated 167 W of output power at 1178 nm using an ytterbium-doped photonic bandgap fiber. Distributed spectral filtering efficiently suppresses amplified spontaneous emission at shorter wavelengths and enables power scalable amplification at 1178nm. (C) 2010 Optical Society of America
International conference proceedings, English

All-Fiber Phase-locked Multi-core Photonic Crystal Fiber Laser with Fill-factor Enhancement and High Efficiency
Akira Shirakawa; Tetsuya Kobayashi; Michio Matsumoto; Ken-ichi Ueda
2010 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (QELS), IEEE, CThO2, 2010, Peer-reviwed, We report large-mode-area Yb-doped 6-core photonic crystal fiber laser in in-phase supermode operation. A monolithic Talbot device, enhancing the fill-factor in fiber and central-lobe fraction in the far-field profile, was demonstrated with 84% slope efficiency. (C)2010 Optical Society of America
International conference proceedings, English

All-Fiber Phase-locked Multi-core Photonic Crystal Fiber Laser with Fill-factor Enhancement and High Efficiency
Akira Shirakawa; Tetsuya Kobayashi; Michio Matsumoto; Ken-ichi Ueda
2010 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (QELS), IEEE, AMC3, 2010, Peer-reviwed, We report large-mode-area Yb-doped 6-core photonic crystal fiber laser in in-phase supermode operation. A monolithic Talbot device, enhancing the fill-factor in fiber and central-lobe fraction in the far-field profile, was demonstrated with 84% slope efficiency. (C)2010 Optical Society of America
International conference proceedings, English

Generation of beams with near-diffraction free propagation characteristics in Yb:YAG laser using an intracavity lens with spherical aberration
M. P. Thirugnanasambandam; Y. Senatsky; A. Shirakawa; K. Ueda
Proc. of The 5th Asian Symposium on Intense Laser Science (ASILS-5), S-09, Dec. 2009, Peer-reviwed
International conference proceedings, English

Generation of cylindrical vector lights from passively Q-switched Nd:YAG laser by using photonic crystal gratings
J. Li; A. Shirakawa; K. Ueda; D. Lin; L. Zhong
レーザー研究, レ-ザ-学会, 37, 11, 806-810, Nov. 2009, Peer-reviwed
Scientific journal, English

Passively Q-switched Nd:YAG ceramic microchip laser with azimuthally polarized output
J.-L. Li; D. Lin; L.-X. Zhong; K. Ueda; A. Shirakawa; M. Musha; W.-B. Chen
Laser Physics Letters, 6, 10, 711-714, Jul. 2009, Peer-reviwed
Scientific journal, English

Crystalline-orientation Selected Linearly Polarized Yb:YAG Microchip Laser
J. Dong; A. Shirakawa; K. Ueda
Proc. of CLEO Europe/EQEC 2009, CA12.6, Jun. 2009, Peer-reviwed
International conference proceedings, English

1178 nm Yb-doped Solid-core Photonic Bandgap Fiber Laser Source for 589nm Generation
H. Maruyama; A. Shirakawa; K. Ueda; C. B. Olausson; J. K. Lyngsø J. Broeng
Proc. of CLEO Europe/EQEC 2009, CJ4.2, Jun. 2009, Peer-reviwed
International conference proceedings, English

Stimulated-emission spectroscopy of fine-grained "garnet" ceramics Nd3+:Y3Al5O12 in a wide temperature range between 77 and 650 K
A. A. Kaminskii; S. N. Bagaev; K. Ueda; A. Shirakawa; M. Tokurakawa; H. Yagi; T. Yanagitani; J. Dong
Laser Phys. Lett., 6, 9, 682-687, Jun. 2009, Peer-reviwed
Scientific journal, English

Circular modes selection in Yb:YAG laser using an intracavity lens with spherical aberration
Yu. Senatsky; J. -F. Bisson; A. Shelobolin; A. Shirakawa; K. Ueda
LASER PHYSICS, MAIK NAUKA/INTERPERIODICA/SPRINGER, 19, 5, 911-918, May 2009, Peer-reviwed, The possibility of use of ordinary short-focus lenses with strong spherical aberration for mode selection in a laser resonator is demonstrated. Plano-convex spherical lenses with foci from 2.5 to 10.0 cm placed inside the resonator of the CW laser diode pumped Yb:YAG laser were used to select circular modes of Laguerre-Gauss and Bessel-Gauss type, or to get ring-like, multi-mode off-axis oscillations with variable inner and outer diameters of rings. At the constant pump power mode selection was obtained by shifting an intracavity lens along the resonator axis relative to the Yb:YAG ceramics active element of 1.1 mm thickness. Peaked and hollow multi-ring beams with output power up to 30 mW were produced. Near diffraction free (ndf) propagation of the central part (minimum or maximum) of these beams was observed along distances over 10 m from the resonator output coupler. The mechanisms of mode selection due to spherical aberration in the resonator and ndf propagation of output beams are considered. The possibility of producing radially polarized beams from the laser with an intracavity lens and possible applications of the devised laser scheme are discussed.
Scientific journal, English

Nonlinear-laser (3)-effects in novel garnet-type fine-grained ceramic-host {YGd2}[Sc2](Al2Ga)O12 for Ln3+ lasants
A. A. Kaminskii; S. N. Bagaev; K. Ueda; H. Yagi; H. J. Eichler; A. Shirakawa; M. Tokurakawa; H. Rhee; K. Takaichi; T. Yanagitani
Laser Phys. Lett., 6, 9, 671-677, May 2009, Peer-reviwed
Scientific journal, English

Ba(Mg,Zr,Ta)O-3:Nd3+ fine-grained ceramics: a novel laser-gain material with disordered structure for high-power laser systems
A. A. Kaminskii; H. Kurakawa; A. Shirakawa; K. Ueda; N. Tanaka; P. Becker; L. Bohaty; M. Akchurin; M. Tokurakawa; S. Kuretake; Y. Kintaka; K. Kageyama; H. Takagi
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 6, 4, 304-310, Apr. 2009, Peer-reviwed, Nd3+-ion doped Ba(Mg,Zr,Ta)O-3 ceramics is introduced as a new gain crystalline materials for lasers and laser amplifiers. By pumping laser-diode radiation at 300 K its CW stimulated emission at 1.0754 mu m wavelength was recorded. Some optical, spectroscopic and mechanical properties were measured as well.
Scientific journal, English

FIBER AMPLIFIERS: Photonic-bandgap fiber amplifier reaches for the stars
C. B. Olausson; J. K. Lyngsø J. Broeng; H. Maruyama; A. Shirakawa
Laser Focus World, 45, 4, Apr. 2009
Research society, English

Diode-pumped ultrashort-pulse generation based on Yb3+:Sc2O3 and Yb3+:Y2O3 ceramic multi-gain-media oscillator
Masaki Tokurakawa; Akira Shirakawa; Ken-ichi Ueda; Hideki Yagi; Meichin Noriyuki; Takagimi Yanagitani; Alexander A. Kaminskii
OPTICS EXPRESS, OPTICAL SOC AMER, 17, 5, 3353-3361, Mar. 2009, Peer-reviwed, Diode- pumped mode-locked laser operation based on Yb3+:Sc2O3 and Yb3+:Y2O3 multi-gain-media oscillator has been demonstrated. 66-fs pulse duration with an average power of 1.5 W and 53-fs pulse duration with an average power of 1 W under 8-W laser diode pumping were achieved. The optical-to-optical efficiency was 18.8%. Additionally, 68-fs pulse duration with an average power of 540 mW from Yb3+:Y2O3 ceramic was also obtained. (c) 2009 Optical Society of America
Scientific journal, English

Ultra-Short Pulses from Diode‐Pumped Yb3+-Doped Crystal and Ceramic Lasers with High Average Power
M. Tokurakawa; A. Shirakawa; K. Ueda; R. Peters; S. T. Fredrich-Thornton; K. Petermann; G. Huber; H. Yagi; T. Yanagitani; A. A. Kaminskii
Advanced Solid-State Photonics 2009, MC3, Feb. 2009, Peer-reviwed
International conference proceedings, English

High-power Yb-doped photonic bandgap fiber amplifier at 1150-1200 nm
A. Shirakawa; H. Maruyama; K. Ueda; C. B. Olausson; J. K. Lyngso; J. Broeng
OPTICS EXPRESS, OPTICAL SOC AMER, 17, 2, 447-454, Jan. 2009, Peer-reviwed, Ytterbium-doped solid-core photonic bandgap fiber amplifiers operating at the long-wavelength edge of the ytterbium gain band are reported. The low-loss bandgap transmission window is formed in the very low gain region, whilst outside the bandgap, large attenuation inhibits the exponential growth of amplified spontaneous emission in the huge-gain 1030-1100 nm region. Hence parasitic-lasing-free, high-power amplification with a marked efficiency is enabled. A 32 W output at 1156 nm with a 66% slope efficiency and 30 W output at 1178 nm with a 58% slope efficiency were successfully obtained. To our knowledge, these are the highest output powers generating from active photonic bandgap fibers, as well as from ytterbium-doped fiber lasers at these wavelengths. (C) 2009 Optical Society of America
Scientific journal, English

高出力Yb添加ファイバーレーザー研究の最前線と展望
白川晃; 植田憲一
光学, 38, 1, 25-32, Jan. 2009, Peer-reviwed
Scientific journal, Japanese

High-power Yb-doped solid-core photonic bandgap fiber amplifier at 1150-1200nm
A. Shirakawa; H. Maruyama; K. Ueda; C. B. Olausson; J. K. Lyngsø B. Mangan; J. Broeng
Photonics West/LASE 2009, 7195-19, Jan. 2009, Peer-reviwed
International conference proceedings, English

30W, 1178nm Yb-doped Photonic Bandgap Fiber Amplifier
Akira Shirakawa; Hiroki Maruyama; Ken-ichi Ueda; Christina B. Olausson; Jens K. Lyngso; Jes Broeng
2009 CONFERENCE ON LASERS AND ELECTRO-OPTICS AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (CLEO/QELS 2009), VOLS 1-5, IEEE, 992-+, 2009, Peer-reviwed, High-power, high-efficiency ytterbium-doped solid-core photonic-bandgap fiber amplification at the long-wavelength edge of the Yb gain band is reported. Amplified-spontaneous-emission-free, 30W non-polarized and 25W linearly-polarized 1178nm outputs have been achieved with <58% slope efficiencies. (C) 2009 Optical Society of America
International conference proceedings, English

Continuous-wave and mode-locked laser operations based on Yb3+:(YGd2)Sc-2(GaAl2)O-12 disordered ceramic
N. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. A. Kaminskii
2009 CONFERENCE ON LASERS AND ELECTRO-OPTICS AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (CLEO/QELS 2009), VOLS 1-5, IEEE, 183-+, 2009, Peer-reviwed, Yb3+:(YGd2)Sc-2(GaAl2)O-12 disordered ceramic has been fabricated. 2.9-W average power with an optical-to-optical efficiency of 44% was achieved in a continuous-wave operation. 112-fs pulse duration with 860-mW average power was also achieved in a mode-locked operation. (C)2009 Optical Society of America
International conference proceedings, English

Passively Q-switched Nd:YAG microchip laser emits radially and azimuth ally polarized light
Jian-Lang Li; Ken-Ichi Ueda; Akira Shirakawa; Lan-Xiang Zhong
CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, CA5.6, 2009, Peer-reviwed
International conference proceedings, English

Generation of near diffraction free beams in Yb:YAG laser using an intracavity lens with spherical aberration
Yu Senatsky; A. Shirakawa; K. Ueda
CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, CA1.5, 2009, Peer-reviwed
International conference proceedings, English

Radially polarized and pulsed output from passively Q-switched Nd:YAG ceramic microchip laser
Jian-lang Li; Ken-ichi Ueda; Mitsuru Musha; Lan-xiang Zhong; Akira Shirakawa
OPTICS LETTERS, OPTICAL SOC AMER, 33, 22, 2686-2688, Nov. 2008, Peer-reviwed, For the first time, to the best of our knowledge, a radially polarized laser pulse was produced from a passively Q-switched Nd:YAG ceramic microchip laser with a piece of Cr(4+):YAG crystal as the saturable absorber and multilayer concentric subwavelength grating as the polarization-selective output coupler. The averaged laser power reached 450 mW with a slope efficiency of 30.2%. The laser pulse had a maximum peak power of 759 W, a minimum pulse duration of 86 ns, and a 6.7 kHz repetition rate at 3.7 W absorbed pump power. The polarization degree of the radially polarized pulse was measured to be as high as 97.4%. Such a radially polarized laser pulse with a high peak power and a short width is important to numerous applications such as metal cutting. (C) 2008 Optical Society of America
Scientific journal, English

High-Power Yb-Doped Solid-Core Photonic Bandgap Fiber Amplifier at 1150-1200nm
H. Maruyama; A. Shirakawa; K. Ueda; C. B. Olausson; J. K. Lyngsø B. Mangan; J. Broeng
Frontiers in Optics/Laser Science XXIV Conference 2008, FTuG5, Oct. 2008, Peer-reviwed
International conference proceedings, English

High-power scaling of Yb fiber laser in the long wavelength range
A. Shirakawa; H. Maruyama; K. Ueda
IEEJ Technical Digest, OQD-08-40, Sep. 2008
Scientific journal, English

A crystalline-orientation self-selected linearly polarized Yb : Y(3)Al(5)O(12) microchip laser
Jun Dong; Akira Shirakawa; Ken-ichi Ueda
APPLIED PHYSICS LETTERS, AMER INST PHYSICS, 93, 10, 101105, Sep. 2008, Peer-reviwed, Crystalline-orientation and pump dependent polarization states of Yb:Y(3)Al(5)O(12) microchip lasers were observed experimentally. Linear polarization was observed at six crystalline orientations in the (111) plane relative to the beam propagation direction along the (111) crystalline axis of Yb:Y(3)Al(5)O(12) crystal. The extinction ratio of the linear polarization decreases and the laser tends to oscillate at random polarization state at high pump power levels. Linear polarization states of Yb:Y(3)Al(5)O(12) microchip laser was selected by the anisotropic spectroscopic properties of the Yb(3+)-ion in cubic Y(3)Al(5)O(12) crystal. The random polarization oscillation at high pump power was caused by the strong thermal-induced birefringence and depolarization. (c) 2008 American Institute of Physics.
Scientific journal, English

Nonlinear-laser effects in NH4H2PO4 (ADP) and ND4D2PO4 (DADP) single crystals: almost two-octave multi-wavelength Stokes and anti-Stokes combs, cascaded lasing in UV and visible ranges with the involving of the second and third harmonic generation
A. A. Kaminskii; V. V. Dolbinina; H. Rhee; H. J. Eichler; K. Ueda; K. Takaichi; A. Shirakawa; M. Tokurakawa; J. Dong; D. Jaque
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 5, 7, 532-542, Jul. 2008, Peer-reviwed, We report the experimental investigation of nonlinear cascaded lasing chi((3)) <-> chi((2)) effects in UV and visible ranges and high-order Stokes and anti-Stokes generation covering spectral space of about 18000 cm(-1) by stimulated Raman scattering and multi-wave mixing processes under one-micron picosecond pumping in the paraelectric state of NH4H2PO4 and ND4D2PO4 single crystals. All recorded Raman induced laser wavelengths are identified and attributed to their SRS-promoting vibration modes. Brief review of nonlinear-laser processes in non-centrosymmetric phosphates of KH2PO4-family and some physical properties of NH4H2PO4 and ND4D2PO4 are given as well.
Scientific journal, English

Efficient excitations of radially and azimuthally polarized Nd3+: YAG ceramic microchip laser by use of subwavelength multilayer concentric gratings composed of Nb2O5/SiO2
Jian-lang Li; Ken-ichi Ueda; Lan-xiang Zhong; Mitsuru Musha; Akira Shirakawa; Takashi Sato
OPTICS EXPRESS, OPTICAL SOC AMER, 16, 14, 10841-10848, Jul. 2008, Peer-reviwed, Cylindrical vector beams were produced from laser diode end-pumped Nd:YAG ceramic microchip laser by use of two types of subwavelength multilayer gratings as the axisymmetric-polarization output couplers respectively. The grating mirrors are composed of high- and low-refractive-index (Nb2O5/SiO2) layers alternately while each layer is shaped into triangle and concentric corrugations. For radially polarized laser output, the beam power reached 610mW with a polarization extinction ratio ( PER) of 61: 1 and a slope efficiency of 68.2%; for azimuthally polarized laser output, the beam power reached 626mW with a PER of 58: 1 and a slope efficiency of 47.6%. In both cases, the laser beams had near-diffraction limited quality. Small differences of beam power, PER and slope efficiency between radially and azimuthally polarized laser outputs were not critical, and could be minimized by further optimized adjustment to laser cavity and the reflectances of respective grating mirrors. The results manifested, by use of the photonic crystal gratings mirrors and end-pumped microchip laser configuration, CVBs can be generated efficiently with high modal symmetry and polarization purity. (C) 2008 Optical Society of America.
Scientific journal, English

Diode-pumped 65 fs Kerr-lens mode-locked Yb3+: Lu2O3 and nondoped Y2O3 combined ceramic laser
Masaki Tokurakawa; Akira Shirakawa; Ken-ichi Ueda; Hideki Yagi; Syunsuke Hosokawa; Takagimi Yanagitani; Alexander A. Kaminskii
OPTICS LETTERS, OPTICAL SOC AMER, 33, 12, 1380-1382, Jun. 2008, Peer-reviwed, Diode-pumped Kerr-lens mode-locked laser operation of Yb3+: Lu2O3 and nondoped Y2O3 combined ceramics has been achieved; 65 fs pulses with an average power of 320 mW under 5 W of pump power were obtained at the center wavelength of 1032 nm. The spectral bandwidth and the time bandwidth product were 18.9 and 0.345 nm, respectively. To our knowledge, this is the first demonstration of a Kerr-lens mode-locked laser operation based on Yb3+: Lu2O3 ceramic. (c) 2008 Optical Society of America.
Scientific journal, English

Circular modes selection in Yb:YAG laser using an intracavity lens with spherical aberration
J.-F. Bisson; A..Shirakawa; K. Ueda; Yu. Senatsky
Laser Optics 2008, TuR1-11, Jun. 2008, Peer-reviwed
International conference proceedings, English

Nonlinear-laser c(3)- and c(2)-effects in fine-grained highly transparent optical Ba(Mg,Zr,Ta)O3 ceramic and their microhardness
A. A. Kaminskii; M. Sh. Akchurin; N. Tanaka; H. J. Eichler; H. Rhee; K. Ueda; K. Takaichi; A. Shirakawa; M. Tokurakawa; J. Dong; Y. Kintaka; S. Kuretake; Y. Sakabe
Phys. Stat. Sol. (a), 205, 7, 1666-1671, May 2008, Peer-reviwed
Scientific journal, English

New nonlinear-laser effects in crystalline fine-grained ceramics based on cubic Sc2O3 and Lu2O3 oxides: second and third harmonic generation, and cascaded self-sum-frequency mixing in UV spectral region
A. A. Kaminskii; H. Rhee; H. J. Eichler; K. Ueda; K. Takaichi; A. Shirakawa; M. Tokurakawa; J. Dong; H. Yagi; T. Yanagitani
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 5, 2, 109-113, Feb. 2008, Peer-reviwed, We report on the first observation of the nonlinear cascading chi((3)) <-> chi((3)) effects in UV spectral range and second harmonic generation stipulated by the "defect" nonlinearity under one-micron pumping in crystalline ceramics based on cubic oxides Sc2O3 and Lu2O3. Broadband their multi-wavelength Stokes and anti-Stokes combs with the extension of 10475 cm(-1) (for Sc2O3) and 8232 cm(-1) (for Lu2O3) were recorded as well.
Scientific journal, English

Mechanical and optical properties of Lu2O3 host-ceramics for Ln3+ lasants
A. A. Kaminskii; M. Sh. Akchurin; P. Becker; K. Ueda; L. Bohaty; A. Shirakawa; M. Tokurakawa; K. Takaichi; H. Yagi; J. Dong; Y. Yanagitani
Laser Phys. Lett., 5, 4, 300-303, Feb. 2008, Peer-reviwed
Scientific journal, English

Diode-pumped sub 100-fs Kerr-lens mode-locking Yb3+:Sc2O3 ceramic laser with high average power
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. Kaminskii
Advanced Solid-State Photonics 2008, WB9, Jan. 2008, Peer-reviwed
International conference proceedings, English

Diode-pumped Kerr-lens mode-locked Yb-doped sesquioxide ceramic laser
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. Kaminskii
APLS 2008, 31Bp4, Jan. 2008, Peer-reviwed
International conference proceedings, English

Diode-pumped Kerr-lens mode-locked Yb3+:Sc2O3 and Yb3+:Y2O3 combined active media ceramic laser
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. Kaminskii
Advanced Solid-State Photonics 2008, postdeadline paper MG2, Jan. 2008, Peer-reviwed
International conference proceedings, English

Diode-pumped sub 60-fs Kerr-lens mode-locked Yb-doped sesquioxide combined ceramic laser
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. A. Kaminskii
2008 CONFERENCE ON LASERS AND ELECTRO-OPTICS & QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE, VOLS 1-9, IEEE, 200-+, 2008, Peer-reviwed, Diode-pumped Kerr-lens mode-locked laser operation of Yb3+:Sc2O3 and Yb3+:Y2O3 combined ceramics has been achieved. Sub-60 fs pulses with the average power of 380 mW were obtained at the center wavelength of 1042 nm. (C)2008 Optical Society of America
International conference proceedings, English

Yb-ASE-free Er amplification in short-wavelength filtered Er : Yb photonic-crystal fiber
Akira Shirakawa; Hiroyuki Suzuki; Motoyuki Tanisho; Ken-ichi Ueda
2008 CONFERENCE ON OPTICAL FIBER COMMUNICATION/NATIONAL FIBER OPTIC ENGINEERS CONFERENCE, VOLS 1-8, OPTICAL SOC AMERICA, 1966-1968, 2008, Peer-reviwed, The short-wavelength cutoff property of photonic-crystal fiber was applied to Er:Yb fiber amplification. Appropriate bending gives >10dB/m distributed filtering in the Yb band and suppression of ASE and parasitic lasing has been successfully demonstrated. (C) 2008 Optical Society of America.
International conference proceedings, English

High-brightness 210 mu J pulsed Raman fiber source
A. Shirakawa; C. A. Codemard; J. Ji; K. K. Chen; A. Malinowski; D. J. Richardson; J. K. Sahu; J. Nilsson
2008 CONFERENCE ON LASERS AND ELECTRO-OPTICS & QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE, VOLS 1-9, IEEE, 1539-1540, 2008, Peer-reviwed, We report a 210 mu J pulsed high-brightness fiber source based on a cladding-pumped Raman fiber. It delivers Stokes light at 1112 nm, of 500 ns duration, 420 W peak power, and W 1.8. (C)2008 Optical Society of America
International conference proceedings, English

Diode-pumped sub 60-fs Kerr-lens mode-locked Yb-doped sesquioxide combined ceramic laser
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. A. Kaminskii
2008 CONFERENCE ON LASERS AND ELECTRO-OPTICS & QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE, VOLS 1-9, IEEE, 200-+, 2008, Peer-reviwed, Diode-pumped Kerr-lens mode-locked laser operation of Yb3+:Sc2O3 and Yb3+:Y2O3 combined ceramics has been achieved. Sub-60 fs pulses with the average power of 380 mW were obtained at the center wavelength of 1042 nm. (C)2008 Optical Society of America
International conference proceedings, English

A crystalline-orientation self-selected linearly polarized Yb: Y 3Al5O12 microchip laser
Jun Dong; Akira Shirakawa; Ken-Ichi Ueda
Applied Physics Letters, 93, 10, CA12.6, 2008, Peer-reviwed, Crystalline-orientation and pump dependent polarization states of Yb: Y3Al5O12 microchip lasers were observed experimentally. Linear polarization was observed at six crystalline orientations in the (111) plane relative to the beam propagation direction along the [111] crystalline axis of Yb: Y3Al5O12 crystal. The extinction ratio of the linear polarization decreases and the laser tends to oscillate at random polarization state at high pump power levels. Linear polarization states of Yb: Y3Al5O12 microchip laser was selected by the anisotropic spectroscopic properties of the Yb 3+ -ion in cubic Y3Al5O12 crystal. The random polarization oscillation at high pump power was caused by the strong thermal-induced birefringence and depolarization. © 2008 American Institute of Physics.
Scientific journal, English

Diode-pumped sub-100 fs Kerr-lens mode-locked Yb3+: Sc2O3 ceramic laser
Masaki Tokurakawa; Akira Shirakawa; Ken-ichi Ueda; Hideki Yagi; Takagimi Yanagitani; Alexander A. Kaminskii
OPTICS LETTERS, OPTICAL SOC AMER, 32, 23, 3382-3384, Dec. 2007, Peer-reviwed, Diode-pumped Kerr-lens mode-locked laser operations of Yb3+:Sc2O3 ceramics have been achieved. 92 fs pulses with the average power of 850 mW under 3.89 W incident pump power were obtained at a center wavelength of 1042 nm. The optical-to-optical efficiency was 21.9%. 90 fs pulses with the average power of 160 mW were also obtained at a center wavelength of 1092 nm. To our knowledge, this is the first demonstration of a Kerr-lens mode-locked Yb3+:Sc2O3 laser. (C) 2007 Optical Society of America.
Scientific journal, English

Picosecond Raman induced Stokes and anti-Stokes lasing in fine-grained Ba(Sn,Zr,Mg,Ta)O-3 crystalline ceramics with the cubic perovskite structure
A. A. Kaminskii; N. Tanaka; H. J. Eichler; H. Rhee; K. Ueda; K. Takaichi; A. Shirakawa; M. Tokurakawa; Y. Kintaka; S. Kuretake; Y. Sakabe
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 4, 11, 819-823, Nov. 2007, Peer-reviwed, We report on the first observation of the Raman induced Stokes and anti-Stokes nonlinear chi((3)) -lasing in crystalline "cubic" Ba(Sn,Zr,Mg,Ta)O-3 ceramics of the E- and Z-types. We believe that these isotropic transparent oxide materials are also promising host-ceramics for lanthanide and transition-metal lasants.
Scientific journal, English

Effect of ytterbium concentration on cw Yb : YAG microchip laser performance at ambient temperature - Part I: Experiments
Jun Dong; A. Shirakawa; K. -I. Ueda; A. A. Kaminskii
APPLIED PHYSICS B-LASERS AND OPTICS, SPRINGER, 89, 2-3, 359-365, Nov. 2007, Peer-reviwed, The microchip laser performance of Yb:YAG crystals doped with different ytterbium concentrations (C-Yb=10, 15, and 20 at. %) has been investigated at ambient temperature without active cooling of the gain media. Efficient laser oscillation for a 1-mm-thick YAG doped with 10 at. % Yb3+ ions was achieved at 1030 and 1049 nm with slope efficiencies of 85% and 81%, correspondingly. The laser performance of heavy-doped Yb:YAG crystals was limited by the thermal population at terminated lasing level and thermal lens effect at room temperature without sufficient cooling of the samples. The laser emitting spectra of Yb:YAG microchip lasers with different Yb concentrations and output couplings are addressed with the local temperature rise, due to the absorption of the pump power inside the gain media under different pump levels.
Scientific journal, English

39-mW annular excitation of ytterbiurn fiber laser with radial polarization
J. -L. Li; K. -I. Ueda; A. Shirakawa; M. Musha; L. -X. Zhong; Z. -M. Zhang
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 4, 11, 814-818, Nov. 2007, Peer-reviwed, An efficient radial-polarization Yb-fiber laser with an intracavity Brewster axicon is demonstrated. The fraction of ASE at low pumping and parasitical oscillation are minimized by adopting bidirectional pumping and angle-polisbed fiber end. So far, except for the improvement in polarization purity and cylindrical symmetry of output beam, 39-mW output power is obtained at 460-mW launched pump power with 13.8% slope efficiency. And also a new type of low-V-parameter multi-mode gain fiber with doughnut concentration distribution of active ions in fiber core profile is predicted to be promising in improving the laser performance further.
Scientific journal, English

Composite Yb : YAG/Cr4+: YAG ceramics picosecond microchip lasers
Jun Dong; Ken-ichi Ueda; Akira Shirakawa; Hideki Yagi; Takagimi Yanagitani; Alexander A. Kaminskii
OPTICS EXPRESS, OPTICAL SOC AMER, 15, 22, 14516-14523, Oct. 2007, Peer-reviwed, Efficient laser-diode pumped picosecond self-Q-switched all-ceramic composite Yb: YAG/ Cr4+: YAG microchip lasers with 0.72 MW peak power has been developed. Lasers with nearly diffraction-limited beam quality (M-2 < 1.09), oscillate at stable single- and multi- longitudinal-modes due to the combined etalon effects in the Yb:YAG and Cr4(+:) YAG parts of its binary structure. (C) 2007 Optical Society of America.
Scientific journal, English

Diode-pumped Kerr-lens mode-locked Yb3+:Sc2O3 ceramic laser
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. A. Kaminskii
3rd Laser Ceramic Symposium, O-L-2, Oct. 2007, Peer-reviwed
International conference proceedings, English

Effect of ytterbium concentration on cw Yb:YAG microchip laser performance at ambient temperature - Part II: Theoretical modeling
J. Dong; A. Shirakawa; K. Ueda; A. A. Kaminskii
Appl. Phys. B, 89, 367-376, Oct. 2007, Peer-reviwed
Scientific journal, English

ファイバーレーザー
白川晃; 植田憲一
プラズマ・核融合学会誌, 83, 8, 702-704, Aug. 2007
Scientific journal, Japanese

New data on investigation of novel laser ceramic on the base of cubic scandium sesquioxide: Two-band tunable CW generation of Yb3+ :Sc2O3 with laser-diode pumping and the dispersion of refractive index in the visible and near-IR of undoped Sc2O3
K. Takaichi; H. Yagi; P. Becker; A. Shirakawa; K. Ueda; L. Bohatý; T. Yanagitani; A. A. Kaminskii
Laser Physics Letters, 4, 7, 507-510, Jul. 2007, Peer-reviwed, We report on the first achievement of tunable two-band "one-micron" CW oscillation in the 2F5/2 → 2F7/2 channel of Yb3+ activator ions in Sc2O3 ceramics with CW laser-diode pumping, as well as on results of precise measurement of the refractive index and its dispersion in spectral range 0.365-2.325 μm and full transmission spectra of undoped Sc2O3 ceramics fabricated by the VSN method. A graph is presented. SE wavelength-output dependences of Yb3+:Sc2O3 ceramic laser with the steadily level 4 W with CW LD-pumping. © 2007 by Astro Ltd.
Scientific journal, English

Laser-diode pumped heavy-doped Yb : YAG ceramic lasers
Jun Dong; Akira Shirakawa; Ken-ichi Ueda; Hideki Yagi; Takagimi Yanagitani; Alexander A. Kaminskii
OPTICS LETTERS, OPTICAL SOC AMER, 32, 13, 1890-1892, Jul. 2007, Peer-reviwed, Laser performance of heavy-doped Yb:YAG ceramics was investigated using a two-pass pumping miniature laser configuration. Slope efficiency of 52% and optical-to-optical efficiency of 48% have been achieved for 1-mm-thick YAG ceramic doped with 20 at. % ytterbium ions. Laser spectra of Yb:YAG ceramic and single-crystal lasers were addressed under different intracavity laser intensities. Heavy-doped Yb:YAG ceramic is more suitable for a thin disk laser than a single-crystal with the same Yb3+-ion lasants. (c) 2007 Optical Society of America.
Scientific journal, English

Converging-axicon-based radially polarized ytterbium fiber laser and evidence on the mode profile inside the gain fiber
Jian-lang Li; Ken-ichi Ueda; Mitsuru Musha; Akira Shirakawa; Zhi-ming Zhang
OPTICS LETTERS, OPTICAL SOC AMER, 32, 11, 1360-1362, Jun. 2007, Peer-reviwed, The radially polarized mode is achieved from an active Yb fiber by utilizing of an intracavity converging axicon, where the axicon acts as a TM01 mode selector based on not only its Brewster convex surface but also the distance between its vertex and plane output coupler. The polarization state of the annular laser beam is checked by using a home-made eight-hole aperture. Furthermore, an uncoated plane glass plate is inserted into the cavity, and the reflected beam points to the existence of an annular lasing mode inside the gain fiber. The issues for developing high-power radially polarized fiber lasers also are considered. (c) 2007 Optical Society of America.
Scientific journal, English

Ytterbium and chromium doped composite Y3Al5O12 ceramics self-Q-switched laser
Jun Dong; Akira Shirakawa; Ken-ichi Ueda; Hideki Yagi; Takagimi Yanagitani; Alexander A. Kaminskii
APPLIED PHYSICS LETTERS, AMER INST PHYSICS, 90, 19, May 2007, Peer-reviwed, Composite Yb:Y3Al5O12/Cr:Y3Al5O12 ceramics were fabricated by using vacuum sintering technique and nanocrystalline technology. Self-Q-switched composite Yb:Y3Al5O12/Cr:Y3Al5O12 ceramic lasers with pulse energy of 125 mu J and peak power of over 105 kW at repetition rate of 3.8 kHz have been demonstrated. Nearly diffraction-limited beam quality with M-2 less than 1.35 was achieved in this composite Yb:Y3Al5O12/Cr:Y3Al5O12 ceramic self-Q-switched lasers. (C) 2007 American Institute of Physics.
Scientific journal, English

High-power ultrashort pulse amplification by use of photonic-crystal fibers
白川晃; 植田憲一
Optical and Electro-Optical Engineering Contact, 45, 4, 195-201, Apr. 2007
Research society, Japanese

Near-diffraction-limited passively Q-switched Yb : Y3Al5O12 ceramic lasers with peak power > 150 kW
Jun Dong; Akira Shirakawa; Ken-ichi Ueda; Hideki Yagi; Takagimi Yanagitani; Alexander A. Kaminskii
APPLIED PHYSICS LETTERS, AMER INST PHYSICS, 90, 13, 131105, Mar. 2007, Peer-reviwed, Laser-diode pumped nearly diffraction-limited beam quality (M-2 < 1.05), high peak power, subnanosecond passively Q-switched Yb:Y3Al5O12 ceramic miniature laser with Cr4+:Y3Al5O12 ceramic as saturable absorber has been achieved. The slope efficiency is as high as 36% for 80% initial transmission of Cr4+:Y3Al5O12 ceramic. The pulse width of 335 ps and peak power of over 150 kW at repetition rate of 5 kHz were obtained. Laser oscillates at single-longitudinal-mode oscillation and wide-separated multilongitudinal-mode oscillation due to the combined etalon effect of the Cr4+:YAG thin plate and thin glass plate as output coupler. (c) 2007 American Institute of Physics.
Scientific journal, English

Switchable pulses generation in passively Q-switched multi longitudinal-mode microchip laser
J. Dong; A. Shirakawa; K. Ueda
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 4, 2, 109-116, Feb. 2007, Peer-reviwed, Periodical switching laser pulses with nanosecond pulse width and several kilowatts peak power from wide-separated multilongitudinal-mode oscillation were observed experimentally in laser-diode pumped passively Q-switched Yb:YAG microchip laser with Cr4+:YAG as saturable absorber. Pulses from different longitudinal modes oscillate alternatively. Periodical pulses oscillation dynamics induced by spatial hole burning effect and mode competition was investigated numerically by the evolution of the inversion population of different modes and the bleaching and recovery of the inversion population of the saturable absorber. The numerical simulations of switchable periodical pulsation of multilongitudinal-mode passively Q-switched Yb:YAG/Cr4+:YAG microchip lasers are in good agreement with experimental results and confirmed that such pulsations are an intrinsic property in passively Q-switched Yb:YAG/Cr4+:YAG microchip lasers.
Scientific journal, English

Diode-pumped 188 fs mode-locked Yb3+: Y2O3 ceramic laser
Masaki Tokurakawa; Kazunori Takaichi; Akira Shirakawa; Ken-ichi Ueda; Hideki Yagi; Takagimi Yanagitani; Alexander A. Kaminskii
APPLIED PHYSICS LETTERS, AMER INST PHYSICS, 90, 7, 071101, Feb. 2007, Peer-reviwed, The authors have demonstrated a diode-pumped passively mode-locked Yb3+:Y2O3 ceramic laser by use of a semiconductor saturable absorber mirror. 188 fs pulses at a center wavelength of 1038 nm are obtained. The maximum output power is 220 mW at an absorbed pump power of 2.4 W with a diffraction-limited beam quality (M2 < 1.1). This is the shortest pulse generation from Yb-doped sesquioxide lasers and ceramic lasers ever reported. (c) 2007 American Institute of Physics.
Scientific journal, English

Low quantum-defect laser oscillation by high intensity pumping at room temperature
Shinichi Matsubara; Kyousuke Uno; Yoshiaki Nakajima; Sakae Kawato; Takao Kobayashi; Akira Shirakawa
Conference on Quantum Electronics and Laser Science (QELS) - Technical Digest Series, 2007, Peer-reviwed, Ytterbium laser oscillations at 980.6 nm and 983.0 nm are observed by high intensity 978.1 nm pumping of around 1 MW/cm2 at room temperature. Corresponding quantum defects are 0.26 % and 0.50 %, respectively. ©2007 Optical Society of America.
International conference proceedings, English

Laser performance of Yb3+: YAG ceramic microchip lasers
Jun Dong; Akira Shirakawa; Ken-ichi Ueda; Hideki Yagi; Takagimi Yanagitani; Alexander A. Kaminskii
SOLID STATE LASERS XVI: TECHNOLOGY AND DEVICES, SPIE-INT SOC OPTICAL ENGINEERING, 6451, 2007, Peer-reviwed, The optical properties of Yb:YAG ceramic doped with different Yb concentrations are presented. The absorption coefficient at peak absorption wavelength of 940 nm increases linearly with Yb concentration in Yb:YAG ceramics. Low-threshold and highly-efficient continuous-wave (cw) laser-diode end-pumped Yb:YAG microchip ceramic laser with near-diffraction-limited beam quality was demonstrated at room temperature. Slope efficiencies of 79%, 67% and optical-to-optical efficiency of 60%, 53% at 1030 nm and 1049 nm, respectively were achieved for 1-mm-thick Yb:YAG ceramic plate (C-Yb = 9.8 at.%) under cw laser-diode pumping. Dual-wavelength operation at 1030 nm and 1049 nm with 5% transmission of the output. coupler was achieved by varying pump power intensity. 1049 nm laser operation was automatically obtained by using 5% transmission output coupler when absorbed pump power is higher than I W. The lasers operate in multi-longitudinal-mode; the effect of pump power on the laser emission spectra for both wavelengths is addressed. The laser wavelength around 1030 nm shifts to short wavelength at low pump power region and then to red with increase of the absorbed pump power, while the laser wavelength around 1049 nm does not change with the pump power. Excellent laser performance indicates Yb:YAG ceramic laser materials could be potentially used in high-power solid-state lasers operating at 1030 nm, 1049 nm, or both wavelengths simultaneously. Laser-diode pumped low-threshold and highly-efficient passively Q-switched Yb:YAG ceramic microchip laser with Cr4+:YAG ceramic as saturable absorber has also been demonstrated. The slope efficiency is as high as 37%, and the optical-to-optical efficiency is as high as 29% for 89% initial transmission of Cr4+:YAG ceramic. The pulse width of 380 ps and peak power of over 82 kW at repetition rate of 12.4 kHz was obtained. Single-longitudinal-mode oscillation and wide-separated multi-longitudinal-mode oscillation due to etalon effect of Cr4+:YAG thin plate was achieved depending on the pump power level.
International conference proceedings, English

Transient temperature profile in the gain medium of CW- and end-pumped passively Q-switched microchip laser
Jianlang Li; Jun Dong; Musha Mitsurua; Akira Shirakawa; Ken-ichi Ueda
Opt. Commun., 270, 1, 63-67, Jan. 2007, Peer-reviwed
Scientific journal, English

Polarization-maintaining fiber pulse compressor by birefringent hollow-core photonic bandgap fiber
Akira Shirakawa; Motoyuki Tanisho; Ken-ichi Ueda
Advanced Solid-State Photonics 2007, MB23, Jan. 2007, Peer-reviwed
International conference proceedings, English

Linearly-polarized Yb-doped fiber laser directly operating at 1178 nm for 589-nm generation
Akira Shirakawa; Jun Ota; Horoki Maruyama; Ken-ichi Ueda
Advanced Solid-State Photonics 2007, MD1, Jan. 2007, Peer-reviwed
International conference proceedings, English

Ambient-temperature 4-W Yb:YAG ceramic microchip lasers at both 1030 nm and 1049 nm
J. Dong; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A.A. Kaminskii
Advanced Solid-State Photonics 2007, WB17, Jan. 2007, Peer-reviwed
International conference proceedings, English

Single-shot fiber dispersionmetry
Akira Shirakawa; Takayuki Atsumi; Motoyuki Tanisho; Ken-Ichi Ueda
OFC/NFOEC 2007 - Optical Fiber Communication and the National Fiber Optic Engineers Conference 2007, OThO1, 2007, Peer-reviwed, A novel white-light interferometry is presented for fiber dispersion measurement. The acquired spectrally-resolved two-dimensional interferogram enables interference-instability-free, instantaneous determination of group delay and dispersion. Various fibers including a birefringent photonic-bandgap fiber were precisely characterized. © 2007 Optical Society of America.
International conference proceedings, English

Linearly-polarized Yb-doped Fiber Laser in an All-fiber Configuration
Akira Shirakawa; Makoto Kamijo; Jun Ota; Ken-ichi Ueda; Kiminori Mizuuchi; Hiroyuki Furuya; Kazuhisa Yamamoto
2007 CONFERENCE ON LASERS & ELECTRO-OPTICS/QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (CLEO/QELS 2007), VOLS 1-5, IEEE, 29-+, 2007, Peer-reviwed, Characteristics of polarization selection in Yb fiber laser by use of birefringent fiber-Bragg gratings are investigated. An 8W, 1064nm linearly-polarized fiber laser with 87% slope efficiency and <20pm bandwidth has been successfully demonstrated. (C)2007 Optical Society of America
International conference proceedings, English

Composite Yb:YAG/Cr:YAG ceramics self-Q-switched laser
Jun Dong; Akira Shirakawa; Ken-ichi Ueda; Hideki Yagi; Takagimi Yanagitani; Alexander A. Kaminskii
2007 CONFERENCE ON LASERS & ELECTRO-OPTICS/QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (CLEO/QELS 2007), VOLS 1-5, IEEE, 1644-+, 2007, Peer-reviwed, Composite Yb:YAG/Cr:YAG ceramics was fabricated successfully by using vacuum sintering technique and nanocrystalline technology. Self-Q-switched lasers with pulse energy of 125 mu J, and peak power of 105 kW have been demonstrated for the first time. (C)2007 Optical Society of America
International conference proceedings, English

Passively Q-switched Yb:YAG/Cr:YAG ceramics miniature lasers with peak power > 150 kW and nearly diffraction-limited beam quality
J. Dong; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani
Conference on Lasers and Electro-Optics Europe - Technical Digest, CA8-3, 2007, Peer-reviwed
International conference proceedings, English

1178nm linearly-polarized all fiber laser
Hiroki Maruyama; Akira Shirakawa; Ken-ichi Ueda
2007 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS, VOLS 1-4, IEEE, 746-747, 2007, Peer-reviwed, We have succeeded in direct lasing at 1178nm with linear polarization from ytterbium-doped fiber. By composing high Q-value cavity with all-fiber configuration, parasitic lasing was suppressed. The output power amounts to 3.03W with 49.5% slope efficiency and bandwidth of 0.037nm. A maximum of 205mW output power at 589nm was obtained at the maximum of 3.03W input power of 1178nm laser.
International conference proceedings, English

Linearly-polarized Yb-doped fiber laser in an all-fiber configuration
Akira Shirakawa; Makoto Kamijo; Jun Ota; Ken Ichi Ueda; Kiminori Mizuuchi; Hiroyuki Furuya; Kazuhisa Yamamoto
Conference on Lasers and Electro-Optics, 2007, CLEO 2007, 19, 20, 1664-1666, 2007, Peer-reviwed, Characteristics of polarization selection in Yb fiber laser by use of birefringent fiber- Bragg gratings are investigated. An 8W, 1064nm linearly-polarized fiber laser with 87% slope efficiency and <20pm bandwidth has been successfully demonstrated. © 2007 Optical Society of America.
International conference proceedings, English

Effect of ytterbium concentration on Yb : YAG microchip laser performance at ambient temperature
Jun Dong; Akira Shirakawa; Ken-ichi Ueda; Alexander A. Kaminskii
2007 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS, VOLS 1-4, IEEE, 89, 359-365, 728-+, 2007, Peer-reviwed, The microchip laser performance of Yb:YAG crystals doped with different ytterbium concentrations (10, 15, and 20 at.%) has been investigated at ambient temperature. Efficient laser oscillation for 1-mm-thick YAG doped with 10 at.% Yb3+ ions was achieved at 1030 and 1049 nm with slope efficiencies of 85 and 81%, correspondingly.
International conference proceedings, English

Self-pulsing dynamics of ytterbium-doped fiber laser with pump-bypassed cavity
J. Li; K. -I. Ueda; M. Musha; A. Shirakawa; L. Zhong
APPLIED PHYSICS B-LASERS AND OPTICS, SPRINGER, 85, 4, 565-569, Dec. 2006, Peer-reviwed, The pump-bypassed laser cavity is suggested as a suitable configuration for investigating the self-pulsing instability in fibre laser. Such arrangement allows access to the residual pump light, which acts as a probe of the intra-cavity dynamics and reflects the inversion variation along the whole gain fibre. We check this method with ytterbium-doped fibre (YDF) laser. The experimental results in original cavity and modified cavity are offered in detail respectively. The analyses of both the temporal traces of the residual pump and laser signal manifest that the various instabilities in YDF laser are associated with the interactions among stimulated emission, pump and/or reabsorption, dependently on the inversion level and also the intensities of the pump and laser intra-cavity signal.
Scientific journal, English

Dual-wavelength-switching operation based on optical bistability in pump-bypassed ytterbium-doped fiber laser
J. -L. Li; M. Musha; A. Shirakawa; K. -I Ueda; L. -X. Zhong
APPLIED PHYSICS B-LASERS AND OPTICS, SPRINGER, 85, 4, 545-548, Dec. 2006, Peer-reviwed, The bistable feature of residual pump in a pump-bypassed Yb-doped fiber laser offers the potential to pump Er/Yb co-doped fiber in a bifurcated cavity for the lasing of the 1537 nm line. The results of our proof-of-concept demonstration show that the oscillations at 1040 nm and 1537 nm are operated in the wavelength-switching mode, and this suggests that the combination of optical bistability in a pump-bypassed fiber laser cavity with a bifurcated cavity could be one simple and efficient method for switchable dual-wavelength operation.
Scientific journal, English

Diode-pumped mode-locked Yb3+: Lu2O3 ceramic laser
M. Tokurakawa; K. Takaichi; A. Shirakawa; K. Ueda; H. Yagi; S. Hosokawa; T. Yanagitani; A. A. Kaminskii
OPTICS EXPRESS, OPTICAL SOC AMER, 14, 26, 12832-12838, Dec. 2006, Peer-reviwed, We report a diode-pumped passively mode-locked Yb3+:Lu2O3 ceramic laser by use of a semiconductor saturable absorber mirror. Almost transform-limited 357 fs pulses at the center wavelength of 1033.5 nm with a maximum average power of 352 mW are obtained. The efficiency against the absorbed pump power is as high as 32% by use of a laser-diode pumping and the repetition rate is 97 MHz. This is the first demonstration of a diode-pumped mode-locked Yb3+:Lu2O3 ceramic laser to our knowledge. (C) 2006 Optical Society of America.
Scientific journal, English

Polarization-maintaining fiber pulse compressor by birefringent hollow-core photonic bandgap fiber
Akira Shirakawa; Motoyuki Tanisho; Ken-ichi Ueda
Opt. Exp., 14, 25, 12039-12048, Nov. 2006, Peer-reviwed
Scientific journal, English

Mode-locking performance of Yb-doped sesquioxide nanocrystalline ceramic lasers
A. Shirakawa; M. Tokurakawa; K. Takaichi; K. Ueda; H. Yagi; S. Hosokawa; T. Yanagitani; A. A. Kaminskii
2nd Laser Ceramic Symposium, 11aAS6, Nov. 2006, Peer-reviwed
International conference proceedings, English

Generation of radially polarized mode in Yb fiber laser by using a dual conical prism
Jian-lang Li; Ken-ichi Ueda; Mitsuru Musha; Akira Shirakawa; Lan-xiang Zhong
OPTICS LETTERS, OPTICAL SOC AMER, 31, 20, 2969-2971, Oct. 2006, Peer-reviwed, For the first time to our knowledge, a radially polarized beam is generated in an Yb-doped multimode double-clad fiber laser by using an intracavity dual conical prism. Up to 6.2 mW of output power is obtained from a 2 m long gain fiber with 7.4% slope efficiency. This research opens a new window to obtaining a radially polarized beam directly from an active fiber. (c) 2006 Optical Society of America.
Scientific journal, English

Sub-nanosecond passively Q-switched Yb:YAG/Cr4+:YAG sandwiched microchip laser
Jun Dong; Akira Shirakawa; Ken-ichi Ueda
Appl. Phys. B: Lasers and Optics, 85, 4, 513-518, Oct. 2006, Peer-reviwed
Scientific journal, English

Diode-pumped mode-locked Yb-doped sesquioxide nanocrystalline ceramic lasers
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; S. Hosokawa; T. Yanagitani; A. A. Kaminskii
OSA Annual Meeting-Frontier in Optics 2006, FMK3, Oct. 2006, Peer-reviwed
International conference proceedings, English

All-ceramic passively Q-switched Yb : YAG/Cr4+ : YAG microchip laser
J. Dong; A. Shirakawa; K. Takaichi; K. Ueda; H. Yagi; T. Yanagitani; A. A. Kaminskii
ELECTRONICS LETTERS, INSTITUTION ENGINEERING TECHNOLOGY-IET, 42, 20, 1154-1156, Sep. 2006, Peer-reviwed, A laser-diode-pumped all-ceramic passively Q-switched Yb:YAG microchip laser with Cr4+:YAG as a saturable absorber has been demonstrated for the first time. A pulse width of 380 ps and a peak power of over 82 kW at a repetition rate of 12.4 kHz was obtained. A slope efficiency of 37% and an optical-to-optical efficiency of 30% was achieved.
Scientific journal, English

New results on characterization of highly transparent C-modification Lu2O3 nanocrystalline ceramics: room-temperature tunable CW laser action of Yb3+ ions under LD-pumping and the propagation kinetics of non-equilibrium acoustic phonons
A. A. Kaminskii; S. N. Bagayev; K. Ueda; K. Takaichi; A. Shirakawa; S. N. Ivanov; E. N. Khazanov; A. V. Taranov; H. Yagi; T. Yanagitani
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 3, 8, 375-379, Aug. 2006, Peer-reviwed, We report on the first achievment of CW oscillation in Yb3+:Lu2O3 ceramic lasers (F-2(5/2) -> F-2(7/2) channel) under LD-pumping at 0.976 mu m wavelength, as well as present of the thickness of grain boundary layers in Lu2O3 ceramics was estimated under non-equilibrium acoustic phonon propagation kinetics at helium temerature (2.4-3.8 K).
Scientific journal, English

Efficient Yb3+: Y3Al5O12 ceramic microchip lasers
Jun Dong; Akira Shirakawa; Ken-ichi Ueda; Hideki Yagi; Takagimi Yanagitani; Alexander A. Kaminskii
APPLIED PHYSICS LETTERS, AMER INST PHYSICS, 89, 9, 091114, Aug. 2006, Peer-reviwed, Low-threshold and highly efficient continuous-wave (cw) Yb3+:Y3Al5O12 (Yb:YAG) ceramic laser with near-diffraction-limited beam quality was demonstrated at room temperature. Dual-wavelength operation at 1030 and 1049 nm with 5% transmission of the output coupler was achieved by varying pump power intensity. Slope efficiencies of 79% at 1030 nm and 67% at 1049 nm were achieved for 1-mm-thick Yb:YAG ceramic plate (C-Yb=9.8 at. %) under cw laser-diode pumping. The effect of pump power on the laser emission spectra of both wavelengths is addressed. Excellent laser performance indicates that Yb:YAG ceramic laser materials could be potentially used in high-power solid-state lasers. (c) 2006 American Institute of Physics.
Scientific journal, English

Maximum value of the pulse energy of a passively Q-switched laser as a function of the pump power
Jianlang Li; Ken-ichi Ueda; Jun Dong; Mitsuru Musha; Akira Shirakawa
APPLIED OPTICS, OPTICAL SOC AMER, 45, 21, 5377-5384, Jul. 2006, Peer-reviwed, The finite recovery time T-s of the bleached absorber is presented as one of the possible mechanisms accounting for the increase-maximum-decrease in pulse energy E with the pumping rate W-p in cw-pumped passively Q-switched solid-state lasers. by analytically evaluating the sign of the derivative partial derivative E/partial derivative W-p. The results show that. in the low punipinie (T > T-s, T is the interpulse period). the initial repopulation density n, remains constant. the final population density n(i) decreases with W-p. and this results in a monotonic increase of E with W-p. In the high pump regime (T < T-s). n, decreases but n(i) remains the same with W-P; this results in a monotonic decrease of E with W-p. At the critical region (T approximate to T), E reaches its maximum value. A cw-pumped Yb:YAG laser passively Q switched by a Cr4-:YAG absorber is demonstrated to confirm this model. The theoretical model is also applied to the analysis of three previously reported passive Q switching solid-state [Nd:GdVO4, Nd-:LaSc3(BO3)(4) (Nd-:LSB), and Nd:YAG] lasers experiments. (c) 2006 Optical Society of America.
Scientific journal, English

Observation of high-order Stokes and anti-Stokes X-(3)-generation in highly transparent laser-host Lu2O3 ceramics
A. A. Kaminskii; S. N. Bagaev; H. J. Eichler; K. Ueda; K. Takaichi; A. Shirakawa; H. Yagi; T. Yanagitani; H. Rhee
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 3, 6, 310-313, Jun. 2006, Peer-reviwed, Efficient room-temperature steady-state high-order stimulated Raman scattering under picosecond laser pumping in ceramics based on cubic Lu2O3 oxide was discovered. All registered Stokes and anti-Stokes generation components were identified and attributed to the chi((3))-promoting vibrations mode omega(SRS) approximate to 392 cm(-1) of this novel crystalline laser-host material.
Scientific journal, English

Residual pump light as a probe of self-pulsing instability in an ytterbium-doped fiber laser
JL Li; K Ueda; M Musha; A Shirakawa
OPTICS LETTERS, OPTICAL SOC AMER, 31, 10, 1450-1452, May 2006, Peer-reviwed, Self-pulsing instability in the ytterbium-doped fiber (YDF) laser is investigated with the pump-bypassed cavity configuration. The residual pump light acts as a probe of the intracavity dynamics, and the temporal behavior of the light shows correlations with the self-mode locking instability in the original cavity and the sustained self-pulsing instability in the modified cavity of the YDF laser. The results suggest that the interactions among stimulated emission, pump absorption and/or reabsorption could account for self-pulsing instability in the YDF laser. The pump-bypassed laser cavity configuration can be used to investigate the instabilities of various kinds of fiber lasers. (c) 2006 Optical Society of America.
Scientific journal, English

Strong optical bistability in ytterbium-doped fibre laser with reabsorption
JL Li; M Musha; A Shirakawa; KI Ueda; L Zhong
ELECTRONICS LETTERS, INSTITUTION ENGINEERING TECHNOLOGY-IET, 42, 8, 449-450, Apr. 2006, Peer-reviwed, The strong optical bistability in a ytterbium-doped fibre (YDF) laser is demonstrated, which is due to the saturable absorption of the unpumped YDF stage. The bistable regions of both the signal output and residual pump light are 320 mW within an antiphase manner with respect to each other. The signal output and residual pump light also exhibit self-pulsing instability. A bifurcated laser cavity configuration for switchable dual-wavelength generation is predicted based on the optical bistability of the residual pump power.
Scientific journal, English

Efficient laser oscillation of Yb : Y3Al5O12 single crystal grown by temperature gradient technique
J Dong; A Shirakawa; K Ueda; J Xu; PZ Deng
APPLIED PHYSICS LETTERS, AMER INST PHYSICS, 88, 16, 161115, Apr. 2006, Peer-reviwed, Low-threshold and highly efficient continuous-wave laser performance of Yb:Y3Al5O12 (Yb:YAG) single crystal grown by a temperature gradient technique (TGT) was achieved at room temperature. The laser can be operated at 1030 and 1049 nm by varying the transmission of the output coupler. Slope efficiencies of 57% and 68% at 1049 and 1030 nm, respectively, were achieved for 10 at. % Yb:YAG sample in continuous-wave laser-diode pumping. The effect of pump power on the laser emission spectrum of both wavelengths is addressed. The near-diffraction-limited beam quality for different laser cavities was achieved. The excellent laser performance indicates that TGT-grown Yb:YAG crystals have very good optical quality and can be potentially used in high-power solid-state lasers.
Scientific journal, English

Switchable lasing of 1040 and 1537-nm lines based on the optical bistability in the pump-bypassed ytterbium-doped fiber laser
Jianlang Li; Mitsuru Musha; Akira Shirakawa; Ken-ichi Ueda
PHOTONIC DEVICES AND ALGORITHMS FOR COMPUTING VIII, SPIE-INT SOC OPTICAL ENGINEERING, 6310, 2006, Peer-reviwed, Lots of attention has been paid to the optical bistability in fiber optical because its potential application in optical information processing and fiber optical communication. Recently the optical bistability in erbium-doped active fiber induced by the nonlinear absorption of the fiber has been investigated. In this paper, we demonstrated the strong optical bistability in the ytterbium-doped fiber laser with the pump-bypassed cavity configuration. In this original configuration, the fiber laser is divided into the gain stage and absorption stage by a WDM. As the function of incident pump power, both the 976nm residual pump intensity and the 1040nm laser signal of this laser exhibit similar to 320mW-wide optical bistabilities in an antiphase manner with respect to each other. Further the residual pump power is directed to pump the second Er and Yb co-doped fiber laser cavity to generate the lasing at 1537mn. As a result of the optical bistability in the residual pump, the lasings of 1040nm and 1537nm are switchable between each other. Worthwhile to point out, these two wavelengths are located in the two wavelength windows applicable for the free-space laser communications, respectively. Therefore the switchable 1040 and 1537nm source by combining the bistable feature of Yb fiber laser with the hybrid cavity configuration (pump-bypassed cavity plus the bifurcated cavity could have important application at this aspect.
International conference proceedings, English

2KHz Single Frequency 1083nm Ytterbium Doped MOPA Fiber Laser System
Shenghong Huang; Guanshi Qin; Akira Shirakawa; Mitsuru Musha; Ken-ichi Ueda
Advanced Solid-State Photonics 2006, WB10, Jan. 2006, Peer-reviwed
International conference proceedings, English

Antiphase dynamics of sub-nanosecond microchip Cr,Yb:YAG self-Q-switched multimode laser
Jun Dong; Akira Shirakawa; Ken-ichi Ueda
Euro. Phys. J. D, 39, 1, 101-106, Jan. 2006, Peer-reviwed
Scientific journal, English

Power scaling of Tm3+ stop doped ZBLAN blue upconversion fiber lasers: modeling and experiments
G Qin; S Huang; Y Feng; A Shirakawa; M Musha; KI Ueda
APPLIED PHYSICS B-LASERS AND OPTICS, SPRINGER, 82, 1, 65-70, Jan. 2006, Peer-reviwed, Power scaling of Tm(3+)s doped ZBLAN blue upconversion fiber lasers was investigated by a simple model. Based on our experimental results on blue fiber lasers, we discuss the effects of photodegradation and photocuring, fiber length, the reflectivity of the coupler mirror and fiber core diameter on further enhancement of blue fiber laser, respectively. The optimal parameters (including fiber length, fiber core diameter and the reflectivity of the coupler mirror) for the operation of high power (> 1 W) blue fiber laser were presented through simple numerical simulations, which are valuable for the future design of high power blue upconversion fiber laser.
Scientific journal, English

Dual-wavelength Laser Performance of Yb:YAG Crystal Grown by Temperature Gradient Technique
Jun Dong; Akira Shirakawa; Ken-ichi Ueda; Jun Xu; Peizhen Deng
Advanced Solid-State Photonics 2006, JWB71, Jan. 2006, Peer-reviwed
International conference proceedings, English

Dispersion-managed all-fiber chirped-pulse amplifier yielding high-power clean sub-500-fs pulses at 1.5 μm
Akira Shirakawa; Motoyuki Tanisho; Ken-Ichi Ueda
Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, CLEO/QELS 2006, JWB71, 2006, Peer-reviwed, All-fiber chirped-pulse amplification based on a large-mode-area Er:Yb-doped photonic-crystal fiber is presented. A dispersion-variable hybrid fiber stretcher compensates the peculiar dispersion of the hollow-core photonic-bandgap fiber compressor yielding transform-limited 440-fs pulses with 1-W average power. © 2006 Optical Society of America.
International conference proceedings, English

Multi-longitudinal-mode oscillation of self-Q-switched Cr,Yb : YAG laser with a plano-concave resonator
J Dong; JL Li; SH Huang; A Shirakawa; K Ueda
OPTICS COMMUNICATIONS, ELSEVIER SCIENCE BV, 256, 1-3, 158-165, Dec. 2005, Peer-reviwed, Stable longitudinal multi-mode chromium and ytterbium co-doped Cr,Yb:YAG self-Q-switched laser formed by a plano-concave resonator has been demonstrated at room temperature without cooling system. An average output power of as much as 70 mW at 1.03 mu n with a pulse width (FWHM) as short as 12.3 ns was obtained with 5% transmission output coupler. High beam quality (M-2<2.4) output with transverse gaussian profile was obtained. The non-linear mode coupling effects of this longitudinal multi-mode laser was investigated and stable pulse sequence was attributed to the non-linear mode coupling effects between main mode oscillation and the side-mode oscillation. (c) 2005 Elsevier B.V. All rights reserved.
Scientific journal, English

Limits of Coherent Addition of Lasers: Simple Estimate
D. Kouznetsov; J-F. Bisson; A. Shirakawa; K. Ueda
Opt. Rev, 12, 6, 445-447, Dec. 2005, Peer-reviwed
Scientific journal, English

1083 nm single frequency ytterbium doped fiber laser
S Huang; Y Feng; J Dong; A Shirakawa; M Musha; K Ueda
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 2, 10, 498-501, Oct. 2005, Peer-reviwed, Single frequency 1083 nm ytterbium fiber laser was demonstrated by introducing loop mirror filter and polarization controller in linear laser cavity. The loop mirror with unpumped ytterbium fiber as a narrow bandwidth filter discriminated and selected laser longitudinal modes efficiently. Spatial hole burning effect was restrained by adjusting polarization controller appropriately. The laser linewidth was about 2 KHz. Output power up to 14 mW were obtained under the launched pump power of 100 mW at 976 nm, the corresponding optical-optical conversion efficiency was 14%, the slope efficiency was 18%a. The measurement of RIN and power stability indicated the stable operation of the laser.
Scientific journal, English

Multiple-wavelength up-conversion laser in Tm3+-doped ZBLAN glass fiber
Guanshi Qin; Shenghong Huang; Yan Feng; Akira Shirakawa; Ken-Ichi Ueda
IEEE Photonics Technology Letters, 17, 9, 1818-1820, Sep. 2005, Peer-reviwed, In this letter, we report on a multiple-wavelength up-conversion laser in Tm3+-doped ZrF4-BaF2-LaF3 -AlF3-NaF glass fiber pumped by an 1120-nm fiber laser. Single-wavelength, two-wavelength, and three-wavelength up-conversion lasers can be obtained by adjusting the distance between the coupler mirror and the fiber end, which is attributed to the frequency-filter effect in the etalon composed of the coupler mirror and the fiber end. The effects of the pump power on the performance of dual-wavelength laser were also discussed. © 2005 IEEE.
Scientific journal, English

Single frequency 1083nm ytterbium doped fiber master oscillator power amplifier laser
SH Huang; GS Qin; A Shirakawa; M Musha; K Ueda
OPTICS EXPRESS, OPTICAL SOC AMER, 13, 18, 7113-7117, Sep. 2005, Peer-reviwed, Single frequency 1083nm ytterbium fiber master oscillator power amplifier system was demonstrated. The oscillator was a linear fiber cavity with loop mirror filter and polarization controller. The loop mirror with unpumped ytterbium fiber as a narrow bandwidth filter discriminated and selected laser longitudinal modes efficiently. Spatial hole burning effect was restrained partially by adjusting polarization controller appropriately in the linear cavity. The amplifier was 5 m ytterbium doped fiber pumped by 976nm pigtail coupled laser diode. The linewidth of the single frequency laser was about 2 KHz. Output power up to 177 mW was produced under the launched pump power of 332 mW. (c) 2005 Optical Society of America
Scientific journal, English

Stable laser-diode pumped microchip sub-nanosecond Cr,Yb : YAG self-Q-switched laser
J Dong; A Shirakawa; S Huang; Y Feng; K Takaichi; M Musha; K Ueda; AA Kaminskii
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 2, 8, 387-391, Aug. 2005, Peer-reviwed, Near-diffraction-limited longitudinal multimode self-Q-switched microchip Cr,Yb:YAG laser is obtained by using of a laser diode as a pump source at room temperature without cooling Cr,Yb:YAG sample. The output Q-switched traces are very stable, and the slope efficiency is as high as 18.5%. Laser pulses with 33.5-mu J pulse energy and 400-ps pulse duration were achieved which results in over 53 kW peak power at repetition rate of 6.6 kHz. The effect of the absorbed pump power on the laser characterization and laser spectrum are addressed in details. The number of the longitudinal laser modes increases with the absorbed pump power.
Scientific journal, English

Scalable ceramic lasers
K Ueda; JF Bisson; H Yagi; K Takaichi; A Shirakawa; T Yanagitani; AA Kaminskii
LASER PHYSICS, IOP PUBLISHING LTD, 15, 7, 927-938, Jul. 2005, Peer-reviwed, Scalable and reliable ceramic lasers were developed by means of the modern ceramic technique. A simple casting technique was applied to the nanocrystalline powder made by the modified urea method. The optical and spectroscopic properties are almost equal to those of single crystals. The scalable ceramic laser materials are really transparent polycrystalline materials useful for expanding the possibilities of solid-state lasers for high-power and short-pulse lasers.
Scientific journal, English

Fiber laser coherent array for power scaling, bandwidth narrowing, and beam direction control
Akira Shirakawa; Keigo Matsuo; Ken-ichi Ueda
OSA TOPS, 83, 547-552, Jul. 2005, Peer-reviwed
Scientific journal, English

Large-mode-area erbium-ytterbium-doped photonic-crystal fiber amplifier yielding 54-kW femtosecond pulses without chirped-pulse amplification
A. Shirakawa; J. Ota; M. Musha; K. Nakagawa; K. Ueda; J. R. Folkenberg; J. Broeng
OSA TOPS, 83, 553-558, Jul. 2005, Peer-reviwed
Scientific journal, English

Photodegradation and photocuring in the operation of a blue upconversion fiber laser
G Qin; S Huang; Y Feng; A Shirakawa; M Musha; KI Ueda
JOURNAL OF APPLIED PHYSICS, AMER INST PHYSICS, 97, 12, Jun. 2005, Peer-reviwed, Photodegradation and photocuring effects were investigated in the operation of a Tm3+-doped blue upconversion fiber laser. Our experimental results indicate that a competition between photodegradation and photocuring greatly affects the maximum output power of a blue upconversion fiber laser. (c) 2005 American Institute of Physics.
Scientific journal, English

Single-frequency fiber laser from linear cavity with loop mirror filter and dual-cascaded FBGs
SH Huang; GS Qin; Y Feng; A Shirakawa; M Musha; KI Ueda
IEEE PHOTONICS TECHNOLOGY LETTERS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 17, 6, 1169-1171, Jun. 2005, Peer-reviwed, A single-frequency ytterbium fiber laser was demonstrated by introducing a loop mirror filter, a polarization controller (PC), and dual-cascaded fiber Bragg gratings (FBGs) in linear laser cavity. The loop mirror with unpumped ytterbium fiber as a narrow bandwidth filter discriminated and selected laser longitudinal modes efficiently. The spatial hole burning effect was restrained by adjusting PC appropriately. Dual closely cascaded FBGs as the output coupler, acting as an etalon, expanded the operation range of single frequency. Output power up to 18 mW at 1064 nm were obtained under the launched pump power of 107 mW at 976 nm, the optical-optical conversion efficiency was about 16.8%; the slope efficiency was about 20%.
Scientific journal, English

Numerical simulation of a diode-laser-pumped self-Q-switched Cr,Yb : YAG microchip laser
J Dong; A Shirakawa; K Ueda
OPTICAL REVIEW, OPTICAL SOC JAPAN, 12, 3, 170-178, May 2005, Peer-reviwed, The dynamic and laser characteristics of the self-Q-switched Cr,Yb:YAG laser were studied by solving the coupled rate equations; the effects of the pump rate, reflectivity of the output couplers and the concentrations of the saturable absorbers on the laser performance were investigated in detail and the numerical simulation of the Cr,Yb:YAG lasers was in good agreement with the experimental data. Better laser performance of the Cr,Yb:YAG self-Q-switched laser can be obtained by using high pump rate, higher concentration of the saturable absorber and suitable reflectivity of the output coupler according to our numerical calculations. A typical self-Q-switched laser pulse of 269.5 W pulse energy with 319 ps pulse width (FWHM) at a repetition rate of 3.1 kHz can be obtained with a monolithic laser cavity, which results in 843.5 kW peak power. (c) 2005 The Optical Society of Japan.
Scientific journal, English

Blue up-conversion fibre laser pumped by a 1120-nm Raman fibre laser
GS Qin; SH Huang; Y Feng; A Shirakawa; M Musha; K Ueda
CHINESE PHYSICS LETTERS, CHINESE PHYSICAL SOC, 22, 5, 1140-1143, May 2005, Peer-reviwed, A Tm3+ -doped ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) fibre up-conversion laser pumped by Raman fibre laser is demonstrated with blue output power levels up to 116mW. For the output mirror with 80% reflectivity, the slope efficiency is about 15%, the optical- to-optical conversion efficiency is 11%, and the maximum un-saturated output power is 116mW. For 60% reflectivity, the slope efficiency is about 18% and the optical-to-optical conversion efficiency is 12%, whilst the maximum saturated output power is about 80 mW due to the existence of photo-degradation effect in Tm3+ doped ZBLAN glass fibre.
Scientific journal, English

シングルモードYb系ファイバーレーザーの高出力化の現状と動向
白川晃; 植田憲一
レーザー研究, 33, 4, 254-261, Apr. 2005, Peer-reviwed
Scientific journal, Japanese

Large-mode-area erbium-ytterbium-doped photonic-crystal fiber amplifier for high-energy femtosecond pulses at 1.55 mu m
A Shirakawa; J Ota; M Musha; K Nakagawa; K Ueda; Folkenberg, JR; J Broeng
OPTICS EXPRESS, OPTICAL SOC AMER, 13, 4, 1221-1227, Feb. 2005, Peer-reviwed, We report a high-energy femtosecond fiber amplifier based on an air-cladded single-transverse-mode erbium-ytterbium-codoped photonic-crystal fiber with a 26-mum mode-field-diameter. 700- fs, 47-MHz pulses at 1557 nm were amplified and compressed to near-transform-limited 100-fs, 7.4-nJ pulses with 54-kW peak powers without chirped-pulse amplification. A linearly polarized output with an extinction ratio exceeding 42 dB was obtained by double-pass configuration. As an application, supercontinuum spanning from 1000 to 2500 nm was generated by a successive 2-m high-nonlinear fiber with a 140-mW average power. (C) 2005 Optical Society of America.
Scientific journal, English

784-nm amplified spontaneous emission from TM3+-doped fluoride glass fiber pumped by an 1120-nm fiber laser
GS Qin; SH Huang; Y Feng; A Shirakawa; K Ueda
OPTICS LETTERS, OPTICAL SOC AMER, 30, 3, 269-271, Feb. 2005, Peer-reviwed, We report 784-nm ((1)G(4) --> H-3(5) transition) amplified spontaneous emission (ASE) from Tm3+ -doped fluoride (ZrF4-BaF2 -LaF3-AlF3-NaF) glass fiber pumped by an 1120-nm fiber laser. To our beast knowledge, this is the first report of 784-nm ((1)G(4) --> H-3(5) transition) ASE in a Tm3+ -doped fluoride fiber laser. Its effects on a 480-nm ((1)G(4) --> H-3(6) transition) blue laser were also discussed. (C) 2005 Optical Society of America.
Scientific journal, English

Lu 2O 3:Yb 3+ ceramics - A novel gain material for high-power solid-state lasers
K. Takaichi; H. Yagi; A. Shirakawa; K. Ueda; S. Hosokawa; T. Yanagitani; A. A. Kaminskii
Physica Status Solidi (A) Applications and Materials Science, 202, 1, R1-R3, Jan. 2005, Peer-reviwed, We have developed Yb 3+:Lu 2O 3 ceramics with nanocrystal-line technology and a vacuum sintering method. A laser diode end-pumped efficient Yb 3+:Lu 2O 3 ceramic laser was demonstrated. A 0.7 W cw output power was obtained with the slope efficiency of ≈36% at 1035 nm wavelength, and 0.95 W with the slope efficiency of ≈53% at 1079 nm. We classify the Lu 2O 3 : Yb 3+ ceramics as gain medium for high-power solid-state lasers © 2005 WILEY-VCH Verlag GmbH &
Co. KGaA, Weinheim.
Scientific journal, English

Blue up-conversion laser in Tm3+ doped ZBLAN glass fiber
GS Qin; S Huang; Y Feng; A Shirakawa; M Musha; K Ueda
2005 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS, IEEE, 428-429, 2005, Peer-reviwed, An 1120nm Raman fiber laser pumped Tm3+-doped ZBLAN fiber up-conversion laser was demonstrated with blue output power levels up to 116mW The effects of the reflectivity of the output coupler mirrors on blue laser were investigated. Based on our experimental results, we also found that there exists a competition between photodegradation and photocuring in the operation of blue fiber laser, which can affect the maximum output power of blue fiber laser greatly.
International conference proceedings, English

Novel cooling technique for operation of quasi four level solid state laser
T Petrov; K Takaichi; H Yoneda; A Shirakawa; A Ueda; N Sabotinov
XV International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers Pt 1 and 2, SPIE-INT SOC OPTICAL ENGINEERING, 5777, 825-828, 2005, Peer-reviwed, We report a novel cooling technique for solid-state laser, which provides opportunity for liquid nitrogen temperature. The cooling holder does not have any windows on the laser beam path in order to minimize dispersion-related effects and nonlinear absorption under femtosecond laser operation. cw laser oscillation of 4% Yb3+-doped Y2O3 ceramics at 120 K temperature and 450 mW output power at 1030 nm, was obtained.
International conference proceedings, English

Antiphase states of sub-nanosecond Cr,Yb : YAG microchip self-Q-switched multimode laser - art. no. 60201C
J Dong; A Shirakawa; K Ueda
Optoelectronic Materials and Devices for Optical Communications, SPIE-INT SOC OPTICAL ENGINEERING, 6020, C201-C201, 2005, Peer-reviwed, The antiphase states were observed experimentally in a laser-diode pumped sub-nanosecond microchip Cr,Yb:YAG self-Q-switched multimode laser which is resulted from the spatial hole burning effect. The stable two-mode, and three-mode oscillation are obtained with the increase of the pump power ratio. The modified multimode rate equations including the spatial hole-burning effect in the active medium and the non-linear absorption of the saturable absorber is proposed. The numerical simulations of the antiphase dynamics of such laser are in good agreement with the experimental data and the antiphase dynamics was explained by the evolution of the inversion population and the bleaching and recovery of the inversion population of the saturable absorber.
International conference proceedings, English

1083nm single frequency ytterbium fiber laser
S Huang; Y Feng; G Qin; A Shirakawa; M Musha; K Ueda
2005 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS, IEEE, 636-637, 2005, Peer-reviwed, 1083nm single frequency ytterbium fiber laser was demonstrated by introducing loop mirror filter and fiber polarization controller in linear cavity. The loop mirror with unpumped ytterbium fiber discriminated and selected laser longitudinal modes efficiently.
International conference proceedings, English

Optimization of the laser performance in Nd3+: YAG ceramic microchip lasers
J Dong; J Lu; A Shirakawa; K Ueda
APPLIED PHYSICS B-LASERS AND OPTICS, SPRINGER, 80, 1, 39-43, Jan. 2005, Peer-reviwed, Based on the four-level system, a theoretical model of diode-laser end-pumped fundamental continuous-wave Nd3+: YAG ceramic microchip lasers is proposed. The fluorescence concentration quenching effect and the absorption efficiency of the host have been taken into account in the model. The theoretical results of the numerical calculations are in good agreement with those of experiments. The effects of the concentration of the Nd3+: YAG ceramic, the thickness of the Nd3+: YAG ceramic, and the transmission of the output coupler on the laser performance ( threshold and output power) are addressed. The optimization of the concentration and the thickness for the Nd3+: YAG ceramic microchip laser is presented. This modeling is not only applicable to the Nd3+: YAG ceramic microchip laser but also to other four-level microchip lasers.
Scientific journal, English

Observation stimulated Raman scattering in nanocrystalline Sc2O3 ceramics
A Kaminskii; SN Bagaev; K Ueda; K Takaichi; J Lu; A Shirakawa; H Hagi; T Yanagitani; HJ Eichler; H Rhee
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 2, 1, 30-35, Jan. 2005, Peer-reviwed, Efficient room-temperature steady-state high-order stimulated Raman scattering under picosecond pumping was excited in highly transparent nanocrystalline ceramics based on cubic SC2O3. All recorded Stokes and anti-Stokes lasing components in the visible and near-IR were identified and attributed to the X-(3)-active vibration mode omega(SRS) approximate to 419 cm(-1) of this novel nonlinear-laser material.
Scientific journal, English

Limits of coherent addition of lasers: simple estimate
D Kouznetsov; JFO Bisson; A Shirakawa; K Ueda
2005 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS, IEEE, 627-629, 2005, Peer-reviwed, The coherent combining of single mode lasers using coupled cavities is considered. A simple analytical estimate of the number of lasers that can be efficiently combined in such a way is suggested. Such an estimate agrees with simulations and experiments reported recently.
International conference proceedings, English

Lu2O3 : Yb3+ ceramics - a novel gain material for high-power solid-state lasers
K Takaichi; H Yagi; A Shirakawa; K Ueda; S Hosokawa; T Yanagitani; AA Kaminskii
PHYSICA STATUS SOLIDI A-APPLIED RESEARCH, WILEY-V C H VERLAG GMBH, 202, 1, R1-R3, Jan. 2005, Peer-reviwed, We have developed Yb3+:Lu2O3 ceramics with nanocrystalline technology and a vacuum sintering method. A laser diode end-pumped efficient Yb-3(+):Lu2O3 ceramic laser was demonstrated. A 0.7 W cw output power was obtained with the slope efficiency of approximate to36% at 1035 nm wavelength, and 0.95 W with the slope efficiency of approximate to53% at 1079 nm. We classify the Lu2O3 : Yb-3(+) ceramics as gain medium for high-power solidstate lasers. (C) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Scientific journal, English

Highly transparent Yb-doped ceramics and the laser-diode-pumped ceramic lasers
K Takaichi; H Yagi; A Shirakawa; K Ueda; T Yanagitani; AA Kaminskii
2005 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS, IEEE, 144-145, 2005, Peer-reviwed, We have been fabricating highly transparent ceramic laser materials. Yb-doped Y3Al5O12 and rare-earth sesquioxide ceramics were developed as laser media. A tunable laser pumped with a 976-nm laser diode was demonstrated with the Yb:Y2O3 ceramics.
International conference proceedings, English

Stable longitudinal multi-mode oscillation in a laser-diode pumped Cr,Yb : YAG self-Q-switched laser
J Dong; XL Li; SH Huang; Y Feng; A Shirakawa; K Ueda
2005 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS, IEEE, 725-726, 2005, Peer-reviwed, Good beam quality, stable longitudinal multi-mode oscillation caused by spatial hole burning was studied in laser-diode pumped Cr,Yb:YAG self-Q-switched microchip laser.
International conference proceedings, English

50-kW, 100-fs pulse generation by large-mode-area erbium-ytterbium-doped photonic-crystal fiber amplifier
A Shirakawa; J Ota; M Musha; K Ueda; Folkenberg, JR; J Broeng
2005 Conference on Lasers & Electro-Optics (CLEO), Vols 1-3, OPTICAL SOC AMERICA, 822-824, 2005, Peer-reviwed, A high-energy femtosecond fiber amplifier using a large-mode-area single-mode erbium-ytterbium-codoped photonic-crystal fiber is presented. 700-fs pulses at 1557nm were amplified and compressed to near-transform-limited 100-fs, 7.4-nJ pulses with > 50-kW peak powers without chirped-pulse amplification. (c) 2005 Optical Society of America
International conference proceedings, English

Fiber laser coherent array for power scaling, bandwidth narrowing, and coherent beam direction control
A Shirakawa; K Matsuo; K Ueda
FIBER LASERS II: TECHNOLOGY, SYSTEMS, AND APPLICATIONS, SPIE-INT SOC OPTICAL ENGINEERING, 5709, 165-174, 2005, Peer-reviwed, Coherent beam combining of many fiber lasers realizes power and brightness scaling. We have proposed and demonstrated highly efficient coherent beam combining of N fiber lasers by Y-shaped array coupled with fused fiber couplers. Power-summed single beam output is obtained from one of the N fiber ports with the lowest loss by selective excitation of one of the N constructive-interference supermodes. The basic characteristics of the coherent array, scalability of power summation, and bandwidth narrowing property will be presented. A 2.65-W fiber laser with only a 12-MHz bandwidth has been obtained by arraying eight 10-nm-bandwidth erbium-doped fiber lasers with an 85% addition efficiency. The characteristic bandwidth narrowing by the Vernier effect can be applied to high-power, narrowband fiber laser beyond nonlinearity limitations. By threshold control of the supermodes, high-speed (> 1 kHz), high-contrast-ratio (> 100) coherent control of beam direction has been demonstrated in the N-8 coherent array. An electro-optically-driven, 8-channel variable optical attenuator array was implemented in the output ports, and the thresholds were controlled electrically. No requirements of complicated phase-control optics/electronics and perfect single beam formation without side lobes are unique advantages. Mass-free and reaction-free properties will be quite useful in material processing and space communications.
International conference proceedings, English

CW7-W, 900-nm-wide supercontinuum source by phosphosilicate fiber Raman laser and high-nonlinear fiber
A Shirakawa; K Ueda
Fiber Lasers II: Technology, Systems, and Applications, SPIE-INT SOC OPTICAL ENGINEERING, 5709, 199-205, 2005, Peer-reviwed, High-power, continuous-wave (CW) supercontinuum spanning from 1200 to 2100 nm has been generated in an all-fiber configuration. The output of a CW 8-W phosphosilicate fiber Raman laser at 1556 nm was efficiently converted to the supercontinuum in the successive high-nonlinear dispersion-shift fiber with the zero-dispersion wavelength of 1539 rim. The fiber-length and input-power dependences were investigated, and both the spectral broadening and continuum power are found to be strongly affected by the 2220-nm absorption band in silica. An average power of 6.8 W and a 20-dB bandwidth of 900 nm were obtained from the optimal 150-m fiber length. Very flat spectral intensity of 10 +/- 1 mW/nm from 1640 to 2015 nm is also a noteworthy feature. Raman-assisted four-wave mixing driven by modulation instability is the most possible mechanism of the presented CW supercontinuum generation and well explains the spectral cutoffs.
International conference proceedings, English

Large-mode-area erbium-ytterbium-doped photonic-crystal fiber amplifier yielding 54-kW femtosecond pulses without chirped-pulse amplification
A Shirakawa; M Musha; KI Ueda; Folkenberg, JR; J Broeng
2005 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS, IEEE, 228-229, 2005, Peer-reviwed, A high-energy femtosecond fiber amplifier using a large-mode-area single-mode erbium-ytterbium-codoped photonic-crystal fiber is presented. 700-fs pulses at 1557nm were amplified and compressed to near-transform-limited 100-fs, 7.4-nJ pulses with > 50-kW peak powers without chirped-pulse amplification.
International conference proceedings, English

All-fiber linearly-polarized Yb-doped fiber laser yielding 2.2-W green second harmonics
A Shirakawa; K Hiwada; S Hasegawa; K Ueda; H Takuma; K Mizuuchi; K Yamamoto; Y Ochi
2005 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS, IEEE, 230-231, 2005, Peer-reviwed, Linearly-polarized, 12-W Yb-doped double-clad fiber laser has been constructed by use of polarization-maintaining fibers and an in-line polarizer. 2.2-W green light was also obtained by second harmonic generation in a periodically-poled MgO:LiNbO3.
International conference proceedings, English

Fiber laser coherent array for power scaling, bandwidth narrowing, and coherent beam direction control
A Shirakawa; K Ueda
2005 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS, IEEE, 624-626, 2005, Peer-reviwed, A 12-MHz-bandwidth fiber laser is reported by coherently arraying eight 10-nm-bandwidth lasers with an 85% addition efficiency. By threshold control of the supermodes, high-speed (> 1kHz), high-contrast-ratio (> 200) beam direction control has been demonstrated.
International conference proceedings, English

High-power CW supercontinuum generation by phosphosilicate fiber Raman laser and high-nonlinear fiber
A Shirakawa; K Ueda
2005 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS, IEEE, 632-633, 2005, Peer-reviwed, Ultrabroad CW continuum spanning from 1200 to 2100nm has been generated with as high as a 7-W power by a simple combination of a 1556-nm fiber Raman laser and high-nonlinear fiber with 1539-nm zero-dispersion wavelength.
International conference proceedings, English

High-power Yb-doped double-clad flber laser directly operating at 1178 nm
J Ota; A Shirakawa; K Ueda
2005 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS, IEEE, 234-235, 2005, Peer-reviwed, We report successful operation of Yb-doped fiber laser at an important wavelength of 1178nm. By optimizing the small-signal gain and Q-value, the output power amounts to 6.5W with 50dB suppression ratio against amplified spontaneous emission.
International conference proceedings, English

Large-mode-area erbium-ytterbium-doped photonic-crystal fiber amplifier yielding 54-kW femtosecond pulses without chirped-pulse amplification
A. Shirakawa; J. Ota; M. Musha; K. Nakagawa; K. Ueda; J. R. Folkenberg; J. Broeng
OSA TOPS, 98, 547-552, 2005, Peer-reviwed
Scientific journal, English

Fiber laser coherent array for power scaling, bandwidth narrowing, and beam direction control
Akira Shirakawa; Keigo Matsuo; Ken-ichi Ueda
OSA TOPS, 98, 553-558, 2005, Peer-reviwed
Scientific journal, English

High-power Yb-doped double-clad fiber laser directly operating at 1178 nm
Jun Ota; Akira Shirakawa; Ken-Ichi Ueda
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest, 2005, 4, 414-415, 2005, Peer-reviwed, We report successful operation of Yb-doped fiber laser at an important wavelength of 1178nm. By optimizing the small-signal gain and Q-value, the output power amounts to 6.5W with 50dB suppression ratio against amplified spontaneous emission.
International conference proceedings, English

Near-field diffractive optical pumping of a laser medium
JF Bisson; A Shirakawa; Y Sato; Y Senatsky; K Ueda
OPTICAL REVIEW, OPTICAL SOC JAPAN, 11, 6, 353-357, Nov. 2004, Peer-reviwed, A Nd:YAG rod active element placed inside a resonator was pumped by the second harmonic radiation (the wavelength lambda = 0.532 mum) of a Q-switched Nd:YAG laser diffracted at a circular aperture. Various distributions of pumping intensity in the Fresnel (near-field) region along the direction of the pump beam diffraction were produced. Inversion profiles with maxima or minima at the resonator axis were formed in the active element, depending on its distance from the circular aperture. Gain-switched operation of the Nd:YAG rod laser at lambda = 1.064 mum is reported at the fundamental mode and also at the TEM(01), TEM(01). and other higher-order modes for different positions of the active element in the near-field region. Applications of such diffractive optical pumping for the concentration of the pumping radiation into the active media and for laser beam profiling are discussed. (C) 2004 The Optical Society of Japan.
Scientific journal, English

First mode-locked ceramic laser: Femtosecond Yb3+: Y2O3 ceramic laser
A Shirakawa; K Takaichi; H Yagi; M Tanisho; JF Bisson; J Lu; K Ueda; T Yanagitani; AA Kaminskii
LASER PHYSICS, INTERPERIODICA, 14, 11, 1375-1381, Nov. 2004, A mode-locked femtosecond ceramic laser based on Yb3+:Y2O3 ceramics is presented. A laser pumped by a 4-W broad-stripe diode was passively mode-locked by semiconductor saturable absorber mirrors. Almost transform-limited 430-fs and 615-fs pulses have been successfully generated at center wavelengths of 1037 and 1076.5 nm with 210 and 420 mW average powers, respectively. The repetition rate was 98 MHz, and the pulse energy and peak power were as high as 4.3 nJ and 7 kW.
Scientific journal, English

Single frequency ytterbium fiber laser from linear cavity with loop mirror filter
SH Huang; Y Feng; G Qin; A Shirakawa; M Musha; K Ueda
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS, INST PURE APPLIED PHYSICS, 43, 10B, L1379-L1381, Oct. 2004, Peer-reviwed, Single frequency ytterbium fiber laser was demonstrated by combining polariztion controller and loop mirror filter in linear laser cavity. Spatial hole burning effect was eliminated by adjusting polarization controller appropriately. The loop mirror with unpumped ytterbium fiber as a narrow bandpass filter can discriminate laser longitudinal modes efficiently. Output power up to 11.7mW at 1064nm were obtained for lauched pump power of 68mW at 976nm, the slope efficiency is about 22%.
Scientific journal, English

Wavefront curvature sensing based on diffraction grating and fractional Fourier transforms
BH Zhu; A Shirakawa; M Musha; K Ueda; KD Cole
OPTICAL REVIEW, OPTICAL SOC JAPAN, 11, 5, 344-347, Sep. 2004, Peer-reviwed, We propose a new concept for wavefront curvature sensing, which is based on diffraction grating and fractional Fourier transforms systems. An explicit formula is derived expressing the wavefront curvature, and the wavefront shape can also be retrieved rapidly. The experimental setup is presented and numerical simulations show the validity of the proposed method. (C) 2004 The Optical Society of Japan.
Scientific journal, English

110 W ceramic Nd3+ : Y3Al5O12 laser
J Lu; H Yagi; K Takaichi; T Uematsu; JF Bisson; Y Feng; A Shirakawa; KI Ueda; T Yanagitani; AA Kaminskii
APPLIED PHYSICS B-LASERS AND OPTICS, SPRINGER, 79, 1, 25-28, Jul. 2004, Peer-reviwed, A high-power, continuous-wave 0.6% Nd3+-doped ceramic Y3Al5O12 (Nd:YAG) laser has been developed. 110 W laser output at 1064 nm was obtained, with a slope efficiency of about 41%. The M-2 factor was found to be around 6. The laser performance of the ceramic laser material was found to compare favorably with that obtained with single crystal Nd:YAG.
Scientific journal, English

高輝度高出力ファイバーレーザー
白川晃; 植田憲一
電気学会論文誌Ｃ, 124, 7, 1367-1374, Jul. 2004, Peer-reviwed
Scientific journal, Japanese

Multiple-color cw visible lasers by frequency sum-mixing in a cascading Raman fiber laser
Y Feng; SH Huang; A Shirakawa; K Ueda
OPTICS EXPRESS, OPTICAL SOC AMER, 12, 9, 1843-1847, May 2004, Peer-reviwed, Multiple cw visible lasers at wavelengths ranging from 550nm to 625nm were generated by intracavity frequency sum-mixing of a cascading Raman fiber laser in a type-I noncritically phase-matched lithium triborate crystal. The phase matching conditions for individual wavelengths were realized by tuning the temperature of the lithium triborate crystal. (C) 2004 Optical Society of America.
Scientific journal, English

Thermal effects in quasi-continuous-wave Nd3+: Y3Al5O12 nanocrystalline-powder random laser
Y Feng; JF Bisson; Lu, JR; SH Huang; K Takaichi; A Shirakawa; M Musha; K Ueda
APPLIED PHYSICS LETTERS, AMER INST PHYSICS, 84, 7, 1040-1042, Feb. 2004, Peer-reviwed, We report an experimental investigation on the thermal effects in a Nd3+:Y3Al5O12 nanocrystalline-powder random laser with a one-mirror structure by quasi-continuous-wave laser diode pumping. Extremely low thermal conductivity in powder and significant temperature dependence of the narrow emission spectrum of Nd3+:Y3Al5O12 leads to a laser line redshift and gain reduction with a higher heat deposit. Mode drifting induced by the temperature dependence of the refractive index is also discussed. (C) 2004 American Institute of Physics.
Scientific journal, English

High-Power, High-Brightness Fiber Laser
Akira Shirakawa; Ken-ichi Ueda
IEEJ Transactions on Electronics, Information and Systems, 124, 7, 1367-1374, 2004, Peer-reviwed, The recent progress of high-power fiber lasers is remarkable. Advantages of a fiber laser in characteristics such as ultra-low loss, high-damage threshold, and waveguide structure enable the outstanding high-power operation with excellent beam quality. In this paper, with the overview of the progressive advances of fiber lasers, our work on high-power fiber lasers is reported. The power limitation of double-clad fiber laser is discussed, which clarifies the importance of scaling the launching capability of pump power. A concept of a fiber-disk laser with a side-pumping geometry was developed and more than 1 kW output power was demonstrated, which is the highest power from a single fiber laser. For further power and brightness scaling, coherent beam combining of many fiber lasers is also investigated. N fiber lasers simply coupled by fused fiber couplers generate power-summed output from one of N fiber ports with high addition efficiencies of more than 85% for N≤8 due to selective excitation of constru tive interference modes. © 2004, The Institute of Electrical Engineers of Japan. All rights reserved.
Scientific journal, English

Highly efficient continuous-wave operation at 1030 and 1075 nm wavelengths of LD-pumped Yb3+: Y2O3 ceramic lasers
K Takaichi; H Yagi; Lu, JR; JF Bisson; A Shirakawa; K Ueda; T Yanagitani; AA Kaminskii
APPLIED PHYSICS LETTERS, AMER INST PHYSICS, 84, 3, 317-319, Jan. 2004, Peer-reviwed, Room-temperature cw laser oscillations at 1030 and 1075 nm wavelengths were demonstrated for the TEM00 mode with Yb3+:Y2O3 ceramics by LD-pumping. A maximum extraction efficiency of 72% at 1075 nm lasing wavelengths and of 45% at 1030 nm lasing wavelengths were observed. (C) 2004 American Institute of Physics.
Scientific journal, English

Nonequilibrium acoustic phonons in Y3Al5O12-based nanocrystalline ceramics
YN Barabanenkov; SN Ivanov; AV Taranov; EN Khazanov; H Yagi; T Yanagitani; K Takaichi; J Lu; JF Bisson; A Shirakawa; K Ueda; AA Kaminskii
JETP LETTERS, MAIK NAUKA/INTERPERIODICA/SPRINGER, 79, 7, 342-345, 2004, Peer-reviwed, The phonon transport processes in high-transparency nanocrystalline laser ceramics based on cubic Y3Al5O12 garnet oxide were investigated by the heat-pulse technique. The propagation kinetics of nonequilibrium acoustic phonons was studied in the range of helium temperatures (1.7-3.8 K). The structural model is suggested for the intergrain layers, and their thickness is estimated. (C) 2004 MAIK "Nauka/Interperiodica".
Scientific journal, English

Measurements of nonlinear refractive indices in ceramic laser media
Y Senatsky; A Shirakawa; Y Sato; J Hagiwara; J Lu; K Ueda; H Yagi; TY Yanagitani
LASER OPTICS 2003: SOLID STATE LASERS AND NONLINEAR FREQUENCY CONVERSION, SPIE-INT SOC OPTICAL ENGINEERING, 5478, 88-97, 2004, Peer-reviwed, At the recent years a technology of ceramic laser media on the base of crystals with a cubic symmetry has been developed. The perspective of the usage of ceramic materials in many different applications including high- power short pulse lasers stimulates the work on the systematic study of the properties of these new laser media. In this report a nonlinear refractive index, n(2), was studied for several garnet and sesquioxide laser ceramics using Z-scan method. This technique with a " top-hat" probe beam intensity distribution was used. Nonlinear indices in the range of (2-6)x10(-13) were measured for YAG,Y2O3, Lu2O3, and Sc2O3 Ceramic samples. These data together with the laser and spectroscopic parameters of several Nd3+ and Yb3+ doped crystals of a cubic symmetry were used to estimate in the complex the properties of laser ceramics for the application in high-power pulsed-repetitive laser - drivers for inertial confinement fusion (ICF) program. A high heat conductivity of ceramic materials is a profitable characteristic for this application as compared to glasses which are used now for experiments in ICF at single shots regime. Compared to single crystals, Ceramic elements provide laser designers with a variety of new design options for the projects of laser-drivers. The usage of ceramic active elements with low and increased n(2) values in the channels of a powerful laser facility is discussed.
International conference proceedings, English

Observation of nonlinear lasing chi((3))-effects in highly transparent nanocrystalline Y2O3 and Y3Al3O12 ceramics
AA Kaminskii; K Ueda; HJ Eichler; SN Bagaev; K Takaichi; J Lu; A Shirakawa; H Yagi; T Yanagitani
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 1, 1, 6-11, Jan. 2004, Peer-reviwed, Multi-wavelength nonlinear parametric chi((3))-effects were observed in highly transparent Y2O3 and Y3Al5O12 nanocrystalline ceramics under picosecond pumping at 300 K. All recorded Stokes and anti-Stokes components in the visible and near IR were identified and attributed to the stimulated Raman scattering active vibration modes of these novel optical and laser-host crystalline materials. For both materials, the steady state first Stokes Raman gain coefficient was estimated at a wavelength of around 1 mum.
Scientific journal, English

Fiber laser coherent array for power scaling of single-mode fiber laser
A Shirakawa; K Matsuo; K Ueda
FIFTH INTERNATIONAL SYMPOSIUM ON LASER PRECISION MICROFABRICATION, SPIE-INT SOC OPTICAL ENGINEERING, 5662, 482-487, 2004, Peer-reviwed, Coherent beam combining of many fiber lasers by the Y-shaped complex resonator method realizes both power scaling and spectral narrowing. The basic characteristics of this Y-shaped coherent array, scalability of power summation, and bandwidth narrowing property are presented. As high as 85% addition efficiency with only a few longitudinal-modes was obtained in an array of eight 10-nm bandwidth lasers coupled by fused fiber couplers. By threshold control of the constructive-interference supermodes, high-speed (>1 kHz), high-contrast-ratio (>100) coherent control of beam direction has also been demonstrated. Mass-free and reaction-free properties can realize high-speed laser-beam scanning, which will be quite useful in many applications such as material processing and space communications.
International conference proceedings, English

Nonlinear refractive index of ceramic laser media and perspectives of their usage in a high-power laser-driver
Yu Senatsky; A. Shirakawa; Y. Sato; J. Hagiwara; J. Lu; K. Ueda; H. Yagi; T. Yanagitani
Laser Physics Letters, 1, 10, 500-506, 2004, Peer-reviwed, At the recent years a technology of ceramic laser media on the base of crystals with a cubic symmetry has been developed. The perspective of the usage of ceramic materials in many different applications including high - power short pulse lasers stimulates the work on the systematic study of the properties of these new laser media. A nonlinear refractive index, n2 was studied for several garnet and sesquioxide laser ceramics using Z-scan method. n2 indices in the range of (2-6) × 10-13 were measured for YAG, Y 2O3, Lu2O3, and Sc2O 3 ceramic samples. These data together with the other laser and spectroscopic parameters of several Nd3+ and Yb3+ doped crystals of a cubic symmetry were used to estimate the properties of laser ceramics for the application in a high-power pulsed-repetitive laser - driver for inertial confinement fusion (ICF) program. A high heat conductivity of ceramic materials is a profitable characteristic for this application as compared to glasses, which are used now for experiments in ICF at single shots regime. Compared to single crystals, ceramic elements provide laser designers with a variety of new design options for the projects of laser-drivers. Transmittance of ceramic sample over the position of a sample along z axis © 2004 by Astro Ltd. Published exclusively by WILEY-VCH Verlag GmbH &
Co. KGaA.
Scientific journal, English

Generation of 10.5 W, 1178 nm laser based on phosphosilicate Raman fiber laser
SH Huang; Y Feng; A Shirakawa; K Ueda
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, INST PURE APPLIED PHYSICS, 42, 12A, L1439-L1441, Dec. 2003, Peer-reviwed, The phosphorous-doped Raman fiber laser fabricated based on a Fabry-Perot cavity is demonstrated. The fiber length (L) values of 300 m and 700 m, and the reflectivity (R) values of the output fiber Bragg grating (FBG) of 15%, 30% and 50% are adopted. Under the optimum configuration of L = 300 m, and R = 15%, a 10.5 W, 1178 nm laser is obtained. Considering the pump power of 19.2 W, the optical-optical conversion efficiency is 54.7% and the corresponding slope efficiency is 80%. The 1178 nm light is frequency-doubled to generate 589 nm light as a source for the laser guide star (LGS) for the mesospheric sodium layer.
Scientific journal, English

Yb3+-doped Y3Al5O12 ceramics - A new solid-state laser material
K Takaichi; H Yagi; J Lu; A Shirakawa; K Ueda; T Yanagitani; AA Kaminskii
PHYSICA STATUS SOLIDI A-APPLIED RESEARCH, WILEY-V C H VERLAG GMBH, 200, 1, R5-R7, Nov. 2003, Peer-reviwed, We have succeeded in the fabrication of Yb3+: Y3Al5O12 ceramics by the nanocrystalline technology and a vacuum sintering method. The first diode end-pumped ceramic laser with this novel solid-state material was demonstrated. The 345-mW cw output power was obtained with the slope efficiency of 26%. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Scientific journal, English

Diode-pumped mode-locked Yb3+: Y2O3 ceramic laser
A Shirakawa; K Takaichi; H Yagi; JF Bisson; J Lu; M Musha; K Ueda
OPTICS EXPRESS, OPTICAL SOC AMER, 11, 22, 2911-2916, Nov. 2003, Peer-reviwed, A diode-pumped femtosecond ytterbium laser with a host material of Y2O3 ceramics is reported. Passive mode locking by a semiconductor saturable-absorber mirror generates 98-MHz, 615-fs pulses at a center wavelength of 1076.5 nm. The average power is 420 mW and the pulse energy is 4.3 nJ with a 2.6-W absorbed pump power. To our knowledge, this is the first continuous-wave mode-locked ceramic laser. (C) 2003 Optical Society of America.
Scientific journal, English

Supercontinuum generation using Raman fiber laser
M Prabhu; A Taniguchi; S Hirose; J Lu; M Musha; A Shirakawa; K Ueda
APPLIED PHYSICS B-LASERS AND OPTICS, SPRINGER-VERLAG, 77, 2-3, 205-210, Sep. 2003, Peer-reviwed, Using a phosphosilicate-doped continuous-wave Raman fiber laser, a 350-m single-mode fiber, and a 50% feedback fiber Bragg grating at 1483.4 nm, we obtained a high-efficiency ultra-broadband (1434 - 1527 nm) supercontinuum (SC) centered at 1483.4 nm with an average Output power of 2.1 W, a spectral intensity of 22.3 mW nm(-1), and a nonlinear conversion efficiency of 94%. Increasing the fiber length in the Raman cavity to 1840 in gave simultaneous SC centered at 1483.4 nm and 1239 nm. An average power of 2.3 W in the bandwidth of 1434-1544 nm and 0.2 W in the bandwidth of 1224-1257 nm is obtained. The temperature dependence of the SC was also investigated.
Scientific journal, English

Yb3+: Sc2O3 ceramic laser
J Lu; JF Bisson; K Takaichi; T Uematsu; A Shirakawa; M Musha; K Ueda; H Yagi; T Yanagitani; AA Kaminskii
APPLIED PHYSICS LETTERS, AMER INST PHYSICS, 83, 6, 1101-1103, Aug. 2003, Peer-reviwed, A solid-state laser material based on highly transparent Yb3+-doped scandia (Sc2O3) ceramic was developed using nanocrystalline technology and the nonpress vacuum sintering method. Continuous wave laser oscillations were obtained at around 1041 and 1094 nm using a 2.5 at. % Yb3+:Sc2O3 ceramic plate. Broadband lasing spectra were observed. (C) 2003 American Institute of Physics.
Scientific journal, English

Laser damage threshold of ceramic YAG
JF Bisson; Y Feng; A Shirakawa; H Yoneda; Lu, JR; H Yagi; T Yanagitani; KI Ueda
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, INST PURE APPLIED PHYSICS, 42, 8B, L1025-L1027, Aug. 2003, Peer-reviwed, Bulk laser damage thresholds of doped and undoped ceramic Y3Al5O12 (YAG) materials are reported. These materials were found to resist 100 J/cm(2), 4-ns pulses at 1.064 mum wavelength. Single-crystal YAG materials of similar composition yielded similar damage thresholds. Hence, ceramic microstructure does not contribute to lower damage threshold. Beam-size dependence of damage threshold fluence was also studied by repeating the experiment using a lens with a longer focal length. The evolution of damage probability with laser fluence was found to strongly depend on the beam diameters however, damage threshold was not found to vary significantly with beam diameter.
Scientific journal, English

Scalable coherent beam combining of fiber lasers
Akira Shirakawa; Tomoki Sekiguchi; Keigo Matsuo; Ken-ichi Ueda
OSA Trends in Optics and Photonics Series, 83, 82-88, Jun. 2003, Peer-reviwed, Coherent addition of W fiber lasers using fiber couplers has been investigated for N-2, 4, and 8. As N increases, higher addition efficiency can be obtained due to suppression of sideband excitation by lineshape narrowing. © 2003 Optical Society of America.
Scientific journal, English

Scalable coherent beam coupling of fiber lasers
Akira Shirakawa; Tomoki Sekiguchi; Ken-Ichi Ueda
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest, Institute of Electrical and Electronics Engineers Inc., 1, 207, 2003, Peer-reviwed, We demonstrated high efficiency coherent coupling between ring-cavity YAG lasers developed for the gravitational wave measurements. A single mode fiber laser is demonstrated for coherent coupling. The coupling efficiency is measured and is found to be limited by the internal loss due to the couplers and the narrow bandwidth of FBGs.
International conference proceedings, English

Promising ceramic laser material: Highly transparent Nd3+: Lu2O3 ceramic
J Lu; K Takaichi; T Uematsu; A Shirakawa; M Musha; K Ueda; H Yagi; T Yanagitani; AA Kaminskii
APPLIED PHYSICS LETTERS, AMER INST PHYSICS, 81, 23, 4324-4326, Dec. 2002, Peer-reviwed, A solid-state laser material based on highly transparent cubic Nd3+:Lu2O3 ceramic was developed using nanocrystalline technology and a nonpress vacuum sintering method. Spectroscopic properties of this ceramic laser material were investigated. At room temperature under single-laser diode pumping, efficient continuous wave laser oscillation was demonstrated at two wavelengths of the F-4(3/2)-->I-4(11/2) channel. The potential application of such a laser material was also discussed. (C) 2002 American Institute of Physics.
Scientific journal, English

Yb3+: Y2O3 ceramics - a novel solid-state laser material
Lu, JR; K Takaichi; T Uematsu; A Shirakawa; M Musha; K Ueda; H Yagi; T Yanagitani; AA Kaminskii
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, INST PURE APPLIED PHYSICS, 41, 12A, L1373-L1375, Dec. 2002, Peer-reviwed, A new solid-state laser based on Yb3+-doped highly transparent nanocrystalline yttria (Y2O3) ceramics was developed. At room temperature and under a pump power of 2.63 W from a single InGaAs laser diode at approximate to 0.94 mum, a continuous-wave laser output of 0.47 W at 1.077 mum wavelength was obtained corresponding to a slope efficiency of about 32%. Some main spectroscopic properties of Yb3+:Y2O3 ceramics were also investigated.
Scientific journal, English

1212 nm pumping of 2 mu m Tm-Ho-codoped silica fiber laser
A Taniguchi; T Kuwayama; A Shirakawa; M Musha; K Ueda; M Prabhu
APPLIED PHYSICS LETTERS, AMER INST PHYSICS, 81, 20, 3723-3725, Nov. 2002, Peer-reviwed, A Tm-Ho-codoped silica fiber laser pumped by a third-stokes Raman Fiber Laser at 1212 nm is demonstrated. For the 30-cm-long Tm-Ho-codoped fiber, a 400 mW output power is obtained at a wavelength of 1790 nm due to the laser emission from the Tm3+ ions. For the 270-cm-long Tm-Ho-codoped fiber, a 450 mW output power is obtained at 1970 nm due to the laser emission from Ho3+ ions. (C) 2002 American Institute of Physics.
Scientific journal, English

Coherent addition of fiber lasers by use of a fiber coupler
A Shirakawa; T Saitou; T Sekiguchi; K Ueda
OPTICS EXPRESS, OPTICAL SOC AMER, 10, 21, 1167-1172, Oct. 2002, Peer-reviwed, Coherent addition of fiber lasers coupled with an intracavity fiber coupler is reported. Almost a single output is obtained from one of the fiber ports, which one can switch simply by unbalancing the losses in the ports. We show that the constructive supermodes, each of which has a single output in a different port, build up automatically because of the dense longitudinal-mode, length-unbalanced laser array with unbalanced port loss. High addition efficiencies of 93.6% for two fiber lasers and 95.6% for four fiber lasers have been obtained. (C) 2002 Optical Society of America.
Scientific journal, English

ファイバーレーザーのコヒーレント加算に関する研究
関口知樹; 斉藤智春; 白川晃; 武者満; 植田憲一
レーザー学会第302回研究会報告 高機能固体レーザーとその応用, RTM-02-25, 23-27, Sep. 2002
Japanese

New highly efficient 1.3 μm CW generation in the 4F3/2 → 4I13/2 channel of the nanocrystalline Nd3+:Y3Al5O12 ceramic laser under diode pumping
Junhua Lu; Jiaren Lu; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; V. Gabler; H. J. Eichler; A. A. Kaminskii
Physica Status Solidi (A) Applied Research, 189, 2, R11-R13, Feb. 2002, Peer-reviwed, Laser potential for efficient oscillation at wavelengths of the second near-infrared (IR) generation channel was demonstrated. The laser spectroscopic properties of Nd3+ ions in Y3Al5O12 ceramics and Y3Al5O12 single crystals were found to be very similar. Characterization showed that the main optical and spectroscopic properties and the thermal conductivity of the Nd3+Y3Al5O12 ceramics and single crystals were identical.
International conference proceedings, English

New highly efficient 1.3 mu m CW generation in the F-4(3/2) -> I-4(13/2) channel of the nanocrystalline Nd3+: Y3Al5O12 ceramic laser under diode pumping
JH Lu; Lu, JR; A Shirakawa; K Ueda; H Yagi; T Yanagitani; Gabler, V; HJ Eichler; AA Kaminskii
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE, WILEY-V C H VERLAG GMBH, 189, 2, R11-R13, Feb. 2002, Peer-reviwed
Scientific journal, English

Chromium doped Y3Al5O12 ceramics - a novel saturable absorber for passively self-Q-switched one-micron solid state lasers
K Takaichi; Lu, JR; T Murai; T Uematsu; A Shirakawa; K Ueda; H Yagi; T Yanagitani; AA Kaminskii
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, INST PURE APPLIED PHYSICS, 41, 2A, L96-L98, Feb. 2002, We demonstrated a laser-diode pumped all ceramic passively self-Q-switched laser with Cr4+:Y3Al5O12 ceramics as a saturable absorber and Nd3+:Y3Al5O12 ceramics as a gain medium. A 190-W peak power was obtained with a 20-ns pulse duration and a 12-kHz repetition rate at approximate to900-mW pumping power. The result indicates that Cr4+:Y3Al5O12 single crystals can be replaced with more productive and cheaper Cr4+:Y3Al5O12 ceramics for many practical solid-state one-micron lasers.
Scientific journal, English

Real-time spectroscopy of molecular vibration using sub-5-fs pulses
T Kobayashi; A Shirakawa; T Fuji
LASER CONTROL AND MANIPULATION OF MOLECULES, AMER CHEMICAL SOC, 821, 171-187, 2002, Peer-reviwed, Transform-limited (TL) visible pulses with as short a duration as 4.7 fs with a 5 muJ pulse energy have been generated for the first time from a novel noncollinear optical parametric amplifier (NOPA). Applications of the sub-5-fs pulse source to the real-time spectroscopy of conjugated polymers, dye molecules, and J-aggregates are described. Several new phenomena, namely mode coupling, dynamic Duschinsky rotation, and dynamic intensity borrowing are found to take place in a polydiacetylene cast film, cresyl violet doped in polymers, and J-aggregates of porphyrin toluene sulfonate in aqueous solution.
Scientific journal, English

Sub-5-fs transform-limited visible pulse source and its application to real-time spectroscopy
T. Kobayashi; A. Shirakawa; T. Fuji
IEEE Journal of Selected Topics in Quantum Electronics, 7, 4, 525-538, Aug. 2001, Peer-reviwed
Scientific journal, English

Supercontinuum generation centered at 1483.4nm and 1239nm using Raman fiber laser
M Prabhu; T Saitou; A Taniguchi; L Jianren; JQ Xu; NS Kim; M Musha; A Shirakawa; K Ueda
CLEO(R)/PACIFIC RIM 2001, VOL II, TECHNICAL DIGEST, IEEE, 156-157, 2001, Peer-reviwed, Simultaneous CW supercontinuum (SC) centered at 1239nm (1218-1260nm) and 1483.4mn (1434-1544nm) is obtained when 350m singlemode fiber is spliced to P-doped cascaded Raman fiber laser. The SC output is investigated for different P-doped fiber lengths.
International conference proceedings, English

Real-time vibrational mode-coupling associated with ultrafast geometrical relaxation in polydiacetylene induced by sub-5-fs pulses
T Kobayashi; A Shirakawa; H Matsuzawa; H Nakanishi
CHEMICAL PHYSICS LETTERS, ELSEVIER SCIENCE BV, 321, 5-6, 385-393, May 2000, Peer-reviwed, The relaxation time of the free-exciton --> geometrically relaxed 2(1)A(g) state in polydiacetylene is determined as 65-80 fs, depending on the probe energy. The vibrational non-equilibrium in the relaxed 2(1)A(g) state is characterized by the modulations of instantaneous frequencies and amplitudes of C-C and C-C stretching modes with a 145-fs oscillation period. The frequency modulation is anti-phase between the two modes, and the amplitude and frequency are also anti-phase for both modes. These are explained by the coupling of the stretching modes through an in-plane bending mode with 230 cm(-1). This is the first real-time observation of dynamic vibrational mode coupling. (C) 2000 Elsevier Science B.V. All rights reserved.
Scientific journal, English

Sub-10-fs tunable pulses in visible and NIR and visible sub-5-fs pulses generated by noncollinear OPA
T Kobayashi; A Shirakawa
JOURNAL OF LUMINESCENCE, ELSEVIER SCIENCE BV, 87-9, 119-120, May 2000, Peer-reviwed, Transform-limited (TL) sub-10-fs pulse was successfully generated with wide tuning ranges in both the visible and near-infrared by introducing a pulse-front-matched (PFM) geometry and spatial dispersion correction to non-collinear optical parametric amplification (NOPA). This is the first report of tunable sub-10-fs pulse generation. A full-bandwidth PFM-NOPA generated the shortest visible pulses 4.7-fs. (C) 2000 Elsevier Science B.V. All rights reserved.
Scientific journal, English

光パラメトリック増幅によるサブ5fsパルスの発生
白川晃
レーザー学会第264回研究会報告, RTM-00-15, 16-19, Jan. 2000
Japanese

Tunable visible and near-infrared pulse generator in a 5 fs regime
T. Kobayashi; A. Shirakawa
Applied Physics B: Lasers and Optics, 70, 1, S239-S246, 2000, Transform-limited (TL) visible pulses with as short a duration as 4.7 fs with a 5 μJ pulse energy have been generated for the first time from a novel noncollinear optical parametric amplifier (NOPA). Both signal-idler group-velocity matching and pulse-front matching are essential to generate coherent down-converted pulses compressible to the TL pulse with more than a 150-THz bandwidth. Tunable operation with bandwidth-limited sub-10-fs pulses in the visible (550-700 nm) and near-infrared (900-1300 nm) ranges, achieved by increasing the seed chirp, is also a remarkable property. The NOPA is believed to be on useful light source for ultrafast spectroscopy on an extremely short time-scale. © Springer-Verlag 2000.
Scientific journal, English

Sub-5-fs visible pulse generation by pulse-front-matched noncollinear optical parametric amplification
A Shirakawa; Sakane, I; M Takasaka; T Kobayashi
APPLIED PHYSICS LETTERS, AMER INST PHYSICS, 74, 16, 2268-2270, Apr. 1999, Peer-reviwed, Sub-5-fs pulses are generated in the visible region. A pulse-front-matched noncollinear optical parametric amplifier is operated with the full bandwidth by precompression of the seeded continuum with a customized ultrabroadband chirped mirror (UBCM) pair. The signal is compressed down to a nearly transform-limited 4.7+/-0.1 fs duration by a prism pair and another UBCM pair with a 5-mu J pulse energy. (C) 1999 American Institute of Physics. [S0003-6951(99)03216-7].
Scientific journal, English

Pulse-front-matched optical parametric amplification for sub-10-fs pulse generation tunable in the visible and near infrared
A Shirakawa; Sakane, I; T Kobayashi
OPTICS LETTERS, OPTICAL SOC AMER, 23, 16, 1292-1294, Aug. 1998, Peer-reviwed, A noncollinear optical parametric amplifier is presented that generates transform-limited sub-10-fs pulses that are tunable in both the visible and the near infrared (NIR). The pulse-front-matched pump geometry realizes tilt-free signal amplification, and pulses as short as 6.1 fs can be obtained from 550 to 700 nm. The large angular dispersion of the idler specific to the group-velocity-matching interaction is effectively eliminated by a grating-telescope compensator, and 9-fs NIR pulses are also successfully obtained from 900 to 1300 nm. This is believed to be the first tunable sub-10-fs Light source. (C) 1998 Optical Society of America.
Scientific journal, English

Noncollinear phase- and group-velocity matching of optical parametric amplifier for ultrashort pulse generation
A Shirakawa; T Kobayashi
IEICE TRANSACTIONS ON ELECTRONICS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E81C, 2, 246-253, Feb. 1998, Peer-reviwed, An ultra-broadband optical parametric amplification can be attained by a noncollinear phase-matching. The group-velocity matching of the signal and idler reduces the signal-pulse width to 14-fs in an optical parametric amplifier based on a beta-BaB2O4 crystal pumped by a second harmonics of a Ti: sapphire regenerative amplifier. This simple novel method shows the potential light source of a tunable sub-10-fs pulse in a visible region.
Scientific journal, English

Noncollinearly phase-matched femtosecond optical parametric amplification with a 2000 cm(-1) bandwidth
A Shirakawa; T Kobayashi
APPLIED PHYSICS LETTERS, AMER INST PHYSICS, 72, 2, 147-149, Jan. 1998, Peer-reviwed, An optical parametric amplifier generating as short as 14 fs pulses in a visible region has been constructed in a noncollinear phase-matching configuration, The group-velocity matching between the signal and idler enormously broadens the gain bandwidth up to 2000 cm(-1), which is mainly limited by the chirp of the-seed pulses. Pulses shorter than 20 fs are tunable from 550 to 690 nm by scanning the delay-line of the pump beam. (C) 1998 American Institute of Physics.
Scientific journal, English

Sub-5-fs pulse generation by pulse-front-matched optical parametric amplification
A Shirakawa; Sakane, I; T Kobayashi
ULTRAFAST PHENOMENA XI, SPRINGER-VERLAG BERLIN, 63, 54-56, 1998, Peer-reviwed, A noncollinear optical parametric amplifier generates shortest 4.7-fs visible pulses or transform-limited sub-9-fs pulses tunable both in the visible (550-700nm) and near-infrared (900-1300nm) for the first time.
International conference proceedings, English

Nonlinear phase shift and detuning by second- and third-order nonlinearities
L Zhang; A Shirakawa; S Morita; T Kobayashi
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS, JAPAN SOC APPLIED PHYSICS, 36, 10A, L1294-L1296, Oct. 1997, Peer-reviwed, We have analyzed the nonlinear phase shift and the wave-number detuning induced by the second-and third-order nonlinearities. Analytical expressions were obtained under the fixed intensity approximation. With a strong pump intensity, the conversion efficiency curve plotted against the phase-mismatch narrows. Due to the detuning effect, the conversion efficiency at perfect phase-matching saturates with the increase of the pump intensity. The experimental result confirms our theory and shows an asymmetric effect caused by the third-order nonlinearity at higher intensity.
Scientific journal, English

Highly efficient generation of blue-orange femtosecond pulses from intracavity-frequency-mixed optical parametric oscillator
A Shirakawa; HW Mao; T Kobayashi
OPTICS COMMUNICATIONS, ELSEVIER SCIENCE BV, 123, 1-3, 121-128, Jan. 1996, Peer-reviwed, The second harmonic generation of the signal or sum frequency generation of the signal and pump in a beta-BaB2O4 crystal in the cavity of an optical parametric oscillator pumped synchronously by a mode-locked Ti:sapphire laser is reported. Visible femtosecond pulses with an average power of 330 mW are generated with a pumping power of 1.3 W. Broad tunability is achieved from 426 to 483 nm and 520 to 585 nm using a single mirror set.
Scientific journal, English

次世代ファイバーレーザー：フォトニックバンドギャップファイバーレーザー
白川晃; 陳明晨
オプトロニクス, Apr. 2015, OPTRONICS, 2015, 4, 148-152, Japanese, Invited, Introduction commerce magazine, 0286-9659, 40020434165, AN00360965

Manifestations of nonlinear optical effects in a novel SRS-active crystal-natural topaz, Al-2(F1-x(OH)(x))(2)SiO4: many-phonon chi((3))-lasing, more than sesqui-octave Stokes and anti-Stokes multi-wavelength comb lasing, cascaded and cross-cascaded chi((3)) <-> chi((3)) Raman-induced interactions under single- and dual-wavelength picosecond collinear coherent pumping, THG and combined SRS-promoting phonon modes
A. A. Kaminskii; O. Lux; H. Rhee; H. J. Eichler; H. Yoneda; A. Shirakawa; K. Ueda; R. Rueckamp; L. Bohaty; P. Becker
Natural crystals of topaz, Al-2(F1-x(OH)(x))(2)SiO4 were found to be an attractive Raman gain material and a subject for the investigation of different chi((3))-nonlinear optical effects. We present several manifestations of photon-phonon interactions related to SRS and RFWM processes initiated by picosecond excitations at room and cryogenic (approximate to 9 K) temperature. Among them are octave-spanning Stokes and anti-Stokes generation in the visible and near-IR spectral range, combined SRS-active phonon modes, cross-cascaded up-conversion, chi((3)) <-> chi((3)) lasing, as well as THG via self-sum frequency parametric generation. All recorded Raman-induced lasing lines are identified and attributed to the promoting chi((3))-vibration transitions. Based on the experimental data, theoretical simulations employing Fourier analysis are performed to demonstrate the potential of wide SRS frequency combs in terms of ultra-short pulse generation., IOP PUBLISHING LTD, Jul. 2013, LASER PHYSICS LETTERS, 10, 7, English, Book review, 1612-2011, 1612-202X, WOS:000320561000001

Laguerre-Gaussian modes selection in diode-pumped solid-state lasers
Yury Senatsky; Jean-Francois Bisson; Jianlang Li; Akira Shirakawa; Manasadevi Thirugnanasambandam; Ken-ichi Ueda
Over the last twenty years, diode pumping of solid-state lasers has opened new prospects for the mode control and formation of Laguerre-Gaussian (LG) beams, enabling a large variety of applications. Experiments on scalar and vector LG modes selection in Nd3+- and Yb3+-doped ceramics and crystal lasers carried out at the Institute for Laser Science, Tokyo are reviewed. Selection of LG modes from low to high orders using intra-cavity elements, polarization-selective mirrors, or shaping the pump beam profile, is considered. Illustrations of record-high-order LG hollow modes, multiring modes with highly directional propagation properties, characteristics of cw and pulsed lasers with radially or azimuthally polarized beams of high polarization purity are presented. General solutions of the wave equation for the axi-symmetric electric field, which describe LG beams of various profiles, are proposed for data analysis. In parallel, a short review on LG modes selection studies carried out at other laboratories is given., OPTICAL SOC JAPAN, Jul. 2012, OPTICAL REVIEW, 19, 4, 201-221, English, Book review, 1340-6000, 1349-9432, WOS:000307271500001

ファイバレーザー
白川晃
オーム社, 2011, 先端固体レーザー, 5, 20001546574

Extremely low quantum defect oscillation of ytterbium fiber laser by laser diode pumping at room temperature
Shinichi Matsubara; Kyousuke Uno; Yoshiaki Nakajima; Sakae Kawato; Takao Kobayashi; Akira Shirakawa
Ytterbium laser emissions at 980.6 nm and 983.0 nm are observed by laser diode pumping at 978.1 nm while room temperature. Their quantum defects are 0.26 % and 0.50 %, respectively. © ptical Society of America. © 2007 Optical Society of America., 01 Jan. 2007, Optics InfoBase Conference Papers, TuB4-1-3, 84898790756

高出力ファイバーレーザーの新展開＝一掃の高出力・高輝度化に向けて＝
白川晃; 植田憲一
日本工業出版, Jan. 2004, 光アライアンス, 15, 1, 20-27, Japanese, Introduction other, 0917-026X, 40006061877, AA11758790

Nd3+: YGdO3 ceramic laser
J Lu; K Takaichi; T Uematsu; A Shirakawa; M Musha; JF Bisson; K Ueda; H Yagi; T Yanagitani; AA Kaminskii
A highly transparent Nd3+:YGdO3 ceramic solid-state laser material was developed using nanocrystalline technology and a nonpress vacuum sintering method. Spectroscopic properties of this ceramic laser material were investigated. Laser diode end-pumped continuous wave laser oscillation was demonstrated at 1078.1 nm in the F-4(3/2) --> I-4(11/2) transition channel., INTERPERIODICA, Jul. 2003, LASER PHYSICS, 13, 7, 940-942, English, Report scientific journal, 1054-660X, WOS:000184313900005

先端固体レーザー
社団法人レ; ザー学会編
Japanese, Joint work, ファイバーレーザー, オーム社, Dec. 2011

RGB3原色・白色光レーザーの開発
白川 晃; 植田憲一
Japanese, Joint work, 透明多結晶セラミックレーザー, サイエンス＆テクノロジー, Jul. 2007

RGB3原色・白色光レーザーの開発
白川 晃; 植田憲一
Japanese, Joint work, 連続発振超広帯域白色ファイバー光源, サイエンス＆テクノロジー, Jul. 2007

光科学研究の最前線
白川晃
Japanese, Joint work, コヒーレントアレイレーザー, 強光子場科学研究懇談会, Aug. 2005

Towards Amplification of All Normal Dispersion Mode-locked Fiber Laser using Multicore Fiber
Yasushi Yogi; Akira Shirakawa
Oral presentation, English, 13th Advanced Lasers and Photon Sources (ALPS '24), OPIC, Peer-reviewed
23 Apr. 2024
22 Apr. 2024- 26 Apr. 2024

Phase Detection using Second Harmonic Generation in Divided Pulse Amplification
Haruyuki Miyake; Kazuki Yoshizawa; Akira Shirakawa
Oral presentation, English, 13th Advanced Lasers and Photon Sources (ALPS '23), OPIC, Peer-reviewed
23 Apr. 2024
22 Apr. 2024- 26 Apr. 2024

高出力ファイバーレーザーの基礎と最新動向
白川晃
Invited oral presentation, Japanese, OPIE ‘24レーザー応用セミナー, Invited
24 Apr. 2024
24 Apr. 2024- 24 Apr. 2024

第二高調波を用いた位相差検出法の分割パルス増幅への適用
三宅晴之; 吉澤和希; 白川晃
Poster presentation, Japanese, レーザー学会第581回研究会「次世代ファイバーレーザー技術」
17 Nov. 2023
17 Nov. 2023- 17 Nov. 2023

マルチコアファイバー増幅のためのシード光源開発
与儀安史; 白川晃
Poster presentation, Japanese, レーザー学会第581回研究会「次世代ファイバーレーザー技術」
17 Nov. 2023
17 Nov. 2023- 17 Nov. 2023

Coherent beam combining using multicore fibers
Akira Shirakawa
Invited oral presentation, English, Advanced Fiber Laser Conference (AFL) 2023, Invited
12 Nov. 2023
10 Nov. 2023- 12 Nov. 2023

Multicore fiber lasers for coherent beam combining
Akira Shirakawa
Nominated symposium, English, UEC-SAARC Symposium on Emerging Technolgies (USSET 2023), Invited
06 Nov. 2023
06 Nov. 2023- 07 Nov. 2023

Time-domain Mode Selection in Multi-mode Fiber Laser by Active Mode Locking
Satoshi Onishi; Akira Shirakawa
Oral presentation, English, Advanced Solid State Lasers (ASSL), 2023 Optica Laser Congress and Exhibition, Peer-reviewed
12 Oct. 2023
08 Oct. 2023- 12 Oct. 2023

マルチコアファイバー増幅のための超短パルス発振器開発
与儀安史; 白川晃
Oral presentation, Japanese, 第84回応用物理学会秋季学術講演会
22 Sep. 2023
19 Sep. 2023- 23 Sep. 2023

分割パルス増幅の第二高調波を用いた位相差検出
三宅晴之; 吉澤和希; 白川晃
Oral presentation, Japanese, 第84回応用物理学会秋季学術講演会
20 Sep. 2023
19 Sep. 2023- 23 Sep. 2023

高出力ファイバーレーザーとビーム結合の基礎
白川晃
Invited oral presentation, Japanese, 第37回光ものづくりセミナー, Invited
26 Jun. 2023
26 Jun. 2023- 26 Jun. 2023

Time-domain Mode Selection in Multi-mode Fiber Laser by Active Mode Locking
Satoshi Onishi; Akira Shirakawa
Oral presentation, 12th Advanced Lasers and Photon Sources (ALPS '23), Peer-reviewed
19 Apr. 2023
18 Apr. 2023- 21 Apr. 2023

高出力ファイバーレーザーの基礎と最新動向
白川晃
OPIE ‘23レーザー応用セミナー, Invited
19 Apr. 2023

高強度ファイバレーザー技術の進展
白川晃
Nominated symposium, レーザー学会学術講演会第43回年次大会, Invited
18 Jan. 2023
18 Jan. 2023- 20 Jan. 2023

マルチモードファイバーレーザーにおける能動モード同期時間領域モード選択のリング型共振器の検討
大西志晶; 白川晃
Poster presentation, レーザー学会第570回研究会「次世代ファイバーレーザー技術」
18 Nov. 2022
18 Nov. 2022- 18 Nov. 2022

可飽和吸収体による位相同期モード同期マルチコアファイバーレーザー発振器に関する研究
森俊介; 白川晃
Poster presentation, レーザー学会第570回研究会「次世代ファイバーレーザー技術」
18 Nov. 2022
18 Nov. 2022- 18 Nov. 2022

マルチモードファイバーにおける能動モード同期時間領域モード選択のリング型共振器の検討
大西志晶; 白川晃
Oral presentation, Japanese, 第83回応用物理学会秋季学術講演会, 応用物理学会, 仙台, Domestic conference
22 Sep. 2022
20 Sep. 2022- 23 Sep. 2022

高出力ファイバーレーザーの基礎と最新動向
白川晃
Invited oral presentation, Japanese, レーザーEXPO 2022レーザー特別セミナー, Invited, レーザーEXPO, 横浜, Domestic conference
20 Apr. 2022
20 Apr. 2022- 22 Apr. 2022

マルチモードファイバーレーザーにおける能動モード同期による時間領域モード選択の研究
大西志晶; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第42回年次大会, レーザー学会, オンライン, Domestic conference
12 Jan. 2022

分割パルスファイバー増幅およびチャープパルス増幅における位相特性と結合効率
杉本洸太; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第42回年次大会, レーザー学会, オンライン, Domestic conference
12 Jan. 2022

ファイバーレーザーのコヒーレントビーム結合技術
白川晃
Invited oral presentation, Japanese, 第1回超高速光エレクトロニクス研究会, Invited, 電子情報通信学会, オンライン, Domestic conference
05 Oct. 2021

位相同期マルチコアファイバレーザ
白川晃
Invited oral presentation, Japanese, 電子情報通信学会ソサイエティ大会, Invited, 電子情報通信学会, オンライン, Domestic conference
16 Sep. 2021

マルチモードファイバーレーザーにおける能動モード同期による時間領域モード選択の研究
大西志晶; 白川晃
Oral presentation, Japanese, 第82回応用物理学会秋季学術講演会, 応用物理学会, オンライン, Domestic conference
11 Sep. 2021

分割パルスファイバー増幅およびチャープパルス増幅による高エネルギー超短パルス増幅特性
杉本洸太; 白川晃
Oral presentation, Japanese, 第82回応用物理学会秋季学術講演会, 応用物理学会, オンライン, Domestic conference
11 Sep. 2021

Phase-locked and mode-locked multicore photonic crystal fiber laser with saturable absorber
Tomonari Kawamura; Akira Shirakawa
Oral presentation, English, CLEO 2021, Optical Society of America, online, International conference
12 May 2021

Kerr-lens mode-locked Yb:CaF2 oscillator directly pumped by a laser diode
Satoshi Nakamura; Yuya Suzuki; Akira Shirakawa
Oral presentation, English, 10th Advanced Lasers and Photon Sources (ALPS '21), 10th Advanced Lasers and Photon Sources (ALPS '21), online, International conference
19 Apr. 2021

Generation of high energy ultrashort pulse using chirped pulse amplification and divided pulse amplification
Kota Sugimoto; Henrik Tünnermann; Akira Shirakawa
Oral presentation, English, 10th Advanced Lasers and Photon Sources (ALPS '21), 10th Advanced Lasers and Photon Sources (ALPS '21), online, International conference
19 Apr. 2021

Phase-locked and mode-locked multicore photonic crystal fiber laser with saturable absorber
Tomonari Kawamura; Akira Shirakawa
Oral presentation, English, Photonics West 2021, SPIE, online, International conference
06 Mar. 2021

Yb添加CaF2結晶を用いたモード同期レーザーの開発
中村聡; 鈴木優哉; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第41回年次大会, レーザー学会, オンライン, Domestic conference
20 Jan. 2021

Yb:CaF2単結晶thin-diskレーザーの開発
鈴木優哉; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第41回年次大会, レーザー学会, オンライン, Domestic conference
20 Jan. 2021

チャープパルス増幅および分割パルス増幅による高エネルギー超短パルスの発生とその位相特性
杉本洸太; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第41回年次大会, レーザー学会, オンライン, Domestic conference
19 Jan. 2021

可飽和吸収体による位相同期モード同期マルチコアフォトニック結晶ファイバーレーザー
川村朋稔; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第41回年次大会, レーザー学会, オンライン, Domestic conference
18 Jan. 2021

カーレンズモード同期Yb:CaF2 超短パルスレーザーの開発
中村聡; 白川晃
Poster presentation, Japanese, 第5回超高速光エレクトロニクス研究会, 情報通信学会超高速光エレクトロニクス研究会, オンライン, Domestic conference
11 Dec. 2020

可飽和吸収体による位相同期モード同期マルチコアフォトニック結晶ファイバーレーザー
川村朋稔; 白川晃
Poster presentation, Japanese, 第5回超高速光エレクトロニクス研究会, 情報通信学会超高速光エレクトロニクス研究会, オンライン, Domestic conference
11 Dec. 2020

分割パルスファイバー増幅およびチャープパルス増幅による高エネルギー超短パルスの発生とその結合効率
杉本洸太; 白川晃
Poster presentation, Japanese, 第5回超高速光エレクトロニクス研究会, 情報通信学会超高速光エレクトロニクス研究会, オンライン, Domestic conference
11 Dec. 2020

モード同期Yb:CaF2単結晶 thin-diskレーザーの研究
鈴木優哉; 白川晃
Poster presentation, Japanese, 第5回超高速光エレクトロニクス研究会, 情報通信学会超高速光エレクトロニクス研究会, オンライン, Domestic conference
11 Dec. 2020

チャープパルス増幅および分割パルス増幅による高エネルギー超短パルスの発生とその位相特性
杉本洸太; 白川晃
Poster presentation, Japanese, レーザー学会第548回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, オンライン, Domestic conference
27 Nov. 2020

可飽和吸収体による位相同期モード同期マルチコアフォトニック結晶ファイバーレーザー
川村朋稔; 白川晃
Oral presentation, Japanese, レーザー学会第548回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, オンライン, Domestic conference
27 Nov. 2020

Yb添加マルチコアフォトニック結晶ファイバーによるファイバー増幅
文全営; 白川晃
Oral presentation, Japanese, 第81回応用物理学会秋季学術講演会, 応用物理学会, オンライン, Domestic conference
08 Sep. 2020

Tiled aperture beam combining with reinforcement learning
Henrik Tünnermann; Akira Shirakawa
Oral presentation, English, CLEO 2020, Optical Society of America, online, International conference
11 May 2020

Mode-locked fiber laser aiming to phase-locked multicore fiber laser
Tomonari Kawamura; Akira Shirakawa
Oral presentation, English, 9th Advanced Lasers and Photon Sources (ALPS '20), 9th Advanced Lasers and Photon Sources (ALPS '20), online, International conference
22 Apr. 2020

Reinforcement learning for tiled aperture beam combining
Henrik Tünnermann; Akira Shirakawa
Oral presentation, English, Photonics West 2020, SPIE, San Francisco, USA, International conference
03 Feb. 2020

マルチモードレーザーの横モード解析の研究
梯太郎; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第40回年次大会, レーザー学会, 仙台, Domestic conference
22 Jan. 2020

マルチコアファイバーレーザーの能動モード同期によるスーパーモード選択の検討
成富未夢人; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第40回年次大会, レーザー学会, 仙台, Domestic conference
22 Jan. 2020

Yb添加BZMTセラミックの光学特性とレーザー発振の検討
池田真由; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第40回年次大会, レーザー学会, 仙台, Domestic conference
21 Jan. 2020

可飽和吸収体によるマルチコアファイバーレーザーの位相同期に向けたモード同期ファイバーレーザー
川村朋稔; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第40回年次大会, レーザー学会, 仙台, Domestic conference
21 Jan. 2020

Yb:CaF2単結晶Thin-diskレーザーの開発
小林祐樹; 北島将太朗; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第40回年次大会, レーザー学会, 仙台, Domestic conference
20 Jan. 2020

半透明thin-disk利得媒質に向けた熱輻射温度モニタリング
鈴木優哉; 小林祐樹; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第40回年次大会, レーザー学会, 仙台, Domestic conference
20 Jan. 2020

Coherent Beam Combining with Deep Reinforcement Learning
H. Tünnermann; A. Shirakawa
Invited oral presentation, English, Advanced Fiber Laser Conference (AFL) 2019, Invited, Advanced Fiber Laser Conference (AFL) 2019, Tianxin, China, International conference
24 Nov. 2019

Yb添加マルチコアファイバー増幅の研究
文全営; 梯太郎; 白川晃
Poster presentation, Japanese, レーザー学会第538回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, 名古屋, Domestic conference
15 Nov. 2019

マルチモードレーザーの横モード解析
梯太郎; 白川晃
Poster presentation, Japanese, レーザー学会第538回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, 名古屋, Domestic conference
15 Nov. 2019

マルチコアファイバーにおける時間領域スーパーモード選択の検討
成富未夢人; 白川晃
Poster presentation, Japanese, レーザー学会第538回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, 名古屋, Domestic conference
15 Nov. 2019

可飽和吸収体によるマルチコアファイバーレーザーの位相同期に向けたモード同期ファイバーレーザーの研究
川村朋稔; 白川晃
Poster presentation, Japanese, レーザー学会第538回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, 名古屋, Domestic conference
15 Nov. 2019

AI Controlled Coherent Beam Combining
H. Tünnermann; A. Shirakawa
Invited oral presentation, English, Advanced Solid-State Lasers (ASSL) 2019, Invited, Optical Society of America, Vienna, Austria, International conference
03 Oct. 2019

可飽和吸収体によるマルチコアファイバーレーザーの位相同期に向けたモード同期ファイバーレーザーの研究
川村朋稔; 白川晃
Oral presentation, Japanese, 第80回応用物理学会秋季学術講演会, 応用物理学会, 札幌, Domestic conference
21 Sep. 2019

OAM Beam via Deep Reinforcement Learning based Coherent Beam Combination
Henrik Tünnermann; Akira Shirakawa
Oral presentation, English, JSAP-OSA Joint Symposia 2019, 第80回応用物理学会秋季学術講演会, 応用物理学会, 札幌, Domestic conference
20 Sep. 2019

Yb3+-doped Ba(Zr,Mg,Ta)O3 ceramic and Yb3+-doped CaF2-LaF3 ceramic
A. Shirakawa; M. Ikeda; S. Kitajima
Invited oral presentation, English, 15th Laser Ceramics Symposium (LCS 2019), Invited, 15th Laser Ceramics Symposium (LCS 2019), Zakopane, Poland, International conference
15 Sep. 2019

Femtosecond Ceramic Thin-Disk Lasers
A. Shirakawa; S. Kitajima
Invited oral presentation, English, Applied Optics and Photonics China (AOPC) 2019, Invited, Applied Optics and Photonics China (AOPC) 2019, Beijing, China, International conference
09 Jul. 2019

AI Controlled Tiled Aperature Coherent Beam Combining
H. Tünnermann; A. Shirakawa
Oral presentation, English, CLEO-Europe/EQEC 2019, CLEO-Europe/EQEC 2019, Munich, Germany, International conference
27 Jun. 2019

Novel Material Ceramics for High-Power Femtosecond Lasers
A. Shirakawa; S. Kitajima
Invited oral presentation, English, 2019 International Advanced Laser Application Summit Forum (ALAT 2019), Invited, 2019 International Advanced Laser Application Summit Forum (ALAT 2019), Shenzhen, China, International conference
09 May 2019

Neural Network Controlled Coherent Beam Combining
H. Tünnermann; A. Shirakawa
Oral presentation, English, 8th Advanced Lasers and Photon Sources (ALPS '19), 8th Advanced Lasers and Photon Sources (ALPS '19), Yokohama, Japan, International conference
25 Apr. 2019

高出力ファイバーレーザーの基礎と最新動向
白川晃
Invited oral presentation, Japanese, レーザーEXPO 2019レーザー特別セミナー, Invited, レーザーEXPO, 横浜, Domestic conference
24 Apr. 2019

Kerr-Lens Mode-Locked Yb:LuAG Ceramic Thin-Disk Laser
S. Kitajima; A. Shirakawa; H. Yagi; T. Yanagitani
Oral presentation, English, 8th Advanced Lasers and Photon Sources (ALPS '19), 8th Advanced Lasers and Photon Sources (ALPS '19), Yokohama, Japan, International conference
22 Apr. 2019

可飽和吸収体によるマルチコアファイバーレーザーの位相同期に向けたモード同期ファイバーレーザーの研究
川村 朋稔; 白川晃
Poster presentation, Japanese, 第19回レーザー学会東京支部研究会, レーザー学会東京支部, 東海大学高輪キャンパス, Domestic conference
08 Mar. 2019

フィゾー干渉計を用いた屈折率の温度係数測定法の改良と評価
鈴木優哉; 北島将太朗; 白川晃
Poster presentation, Japanese, 第19回レーザー学会東京支部研究会, レーザー学会東京支部, 東海大学高輪キャンパス, Domestic conference
08 Mar. 2019

Reinforcement learning for coherent beam combination
Henrik Tünnermann; Akira Shirakawa
Oral presentation, English, Photonics West 2019, SPIE, San Francisco, USA, International conference
06 Feb. 2019

Yb添加Ba(Zr,Mg,Ta)O3セラミックレーザーの研究
池田真由; 北島将太朗; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第39回年次大会, レーザー学会, 東京, Domestic conference
14 Jan. 2019

単層カーボンナノチューブを用いたYb:CaF2-LaF3セラミックモード同期レーザーの開発
小林祐樹; 北島将太朗; 山角謙太郎; 白川晃; 原田昌樹; 石沢均
Oral presentation, Japanese, レーザー学会学術講演会第39回年次大会, レーザー学会, 東京, Domestic conference
14 Jan. 2019

Nonlinear Effects and Combining Efficiency in Divided Pulse Amplification
Ei Jo(Rui Xu; Henrik Tunnermann; Akira Shirakawa
Oral presentation, English, レーザー学会学術講演会第39回年次大会, レーザー学会, 東京, Domestic conference
14 Jan. 2019

マルチコアファイバーレーザーの横モード解析
梯太郎; Henrik Tünnermann; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第39回年次大会, レーザー学会, 東京, Domestic conference
12 Jan. 2019

能動モード同期によるマルチコアファイバーのスーパーモード選択
成富未夢人; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第39回年次大会, レーザー学会, 東京, Domestic conference
12 Jan. 2019

高出力ファイバーレーザーの基礎と最新動向
白川晃
Invited oral presentation, Japanese, レーザー学会東京支部セミナー, Invited, レーザー学会東京支部, 調布, Domestic conference
30 Nov. 2018

Kerr-lens mode-locked thin-disk lasers of Lu-based oxide ceramic gain media
S. Kitajima; A. Shirakawa; H. Yagi; T. Yanagitani
Poster presentation, English, 14th Laser Ceramics Symposium (LCS 2018), Laser Ceramics Symposium, Okazaki, Japan, International conference
29 Nov. 2018

Mode-locked Yb CaF2-LaF3 ceramic laser using single-walled carbon nanotube saturable absorber
Y. Kobayashi; S. Kitajima; K. Yamakado; A. Shirakawa; M. Harada; H.Ishizawa
Poster presentation, English, 14th Laser Ceramics Symposium (LCS 2018), Laser Ceramics Symposium, Okazaki, Japan, International conference
29 Nov. 2018

Study of Yb3+-doped Ba(Zr,Mg,Ta)O3 ceramic laser
M. Ikeda; S. Kitajima; A. Shirakawa
Poster presentation, English, 14th Laser Ceramics Symposium (LCS 2018), Laser Ceramics Symposium, Okazaki, Japan, International conference
29 Nov. 2018

Artificial Intelligence for coherent beam combining
Henrik Tünnermann; Akira Shirakawa
Oral presentation, English, レーザー学会第525回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, 名古屋, Domestic conference
16 Nov. 2018

音響光学変調器を用いたマルチコアファイバーのスーパーモード選択
成富未夢人; 白川晃
Poster presentation, Japanese, レーザー学会第525回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, 名古屋, Domestic conference
16 Nov. 2018

マルチコアファイバーレーザーの横モード解析
梯太郎; 白川晃
Poster presentation, Japanese, レーザー学会第525回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, 名古屋, Domestic conference
16 Nov. 2018

Nonlinearities in Divided Pulse Amplification
Ei Jo; Koji Iwata; Henrik Tünnermann; Akira Shirakawa
Poster presentation, English, レーザー学会第525回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, 名古屋, Domestic conference
16 Nov. 2018

Sub-100 fs Kerr-Lens Mode-Locked Thin-Disk Lasers Based on Ceramic Gain Media
S. Kitajima; A. Shirakawa; H. Yagi; T. Yanagitani
Oral presentation, English, Advanced Solid-State Lasers (ASSL) 2018, Optical Society of America, Boston, USA, International conference
08 Nov. 2018

Coherent Beam Combination via deep reinforcement learning
Henrik Tünnermann; Akira Shirakawa
Oral presentation, English, JSAP-OSA Joint Symposia 2018, 第79回応用物理学会秋季学術講演会, 応用物理学会, 名古屋, Domestic conference
21 Sep. 2018

Kerrレンズモード同期Yb:LuAGセラミック薄ディスクレーザー
北島将太朗; 白川晃; 八木秀喜; 柳谷高公
Oral presentation, Japanese, 第79回応用物理学会秋季学術講演会, 応用物理学会, 名古屋, Domestic conference
19 Sep. 2018

End-to-end reinforcement learning for coherent beam combination
H. Tünnermann; A. Shirakawa
Poster presentation, English, 8th EPS-QEOD Europhoton Conference, European Physical Society, Barcelona, Spain, International conference
04 Sep. 2018

Reinforcement Learning for Coherent Beam Combining
H. Tünnermann; A. Shirakawa
Oral presentation, English, CLEO-PR 2018, CLEO-PR 2018, Hong Kong, International conference
01 Aug. 2018

位相同期マルチコアファイバーレーザーの最近の展開
白川晃
Poster presentation, Japanese, レーザー学会 「ファイバーレーザー技術」専門委員会 第2回委員会, レーザー学会 「ファイバーレーザー技術」専門委員会, 休暇村支笏湖, Domestic conference
27 Jul. 2018

High Power Urtrashort Pulse Laser Based On Yb-doped Ceramic Materials
S. Kitajima; A. Shirakawa; H. Yagi; T. Yanagitani; H. Ishizawa
Invited oral presentation, English, 2018 Glass and Optical Materials Division (GOMD) Meeting, Invited, American Ceramic Society, San Antonio, Texas, USA, International conference
22 May 2018

177 fs pulses from Kerr-lens mode-locked Yb:Lu2O3 ceramic thin-disk laser
S. Kitajima; A. Shirakawa; H. Yagi; T. Yanagitani
Poster presentation, English, 7th Advanced Lasers and Photon Sources (ALPS '18), 7th Advanced Lasers and Photon Sources (ALPS '18), Yokohama, Japan, International conference
26 Apr. 2018

Mode analysis in phase-locked multicore fiber laser by interference method
A. Shirakawa; Y. Kurosu; H. Tünnermann
Poster presentation, English, Photonics Europe 2018, SPIE, Strasbourg, France, International conference
23 Apr. 2018

Coherent beam combining for power scaling of fiber lasers
A. Shirakawa; H. Tünnerman
Invited oral presentation, English, The 10th Asian Symposium on Intense Laser Science (ASILS10), Invited, The 10th Asian Symposium on Intense Laser Science (ASILS10), Sharjah, UAE, International conference
12 Mar. 2018

Kerr-lens mode-locked Yb:Lu2O3 ceramic thin-disk laser
S. Kitajima; A. Shirakawa
Poster presentation, English, CIAiS International Symposium 2018, CIAiS, Tokyo, Japan, International conference
08 Mar. 2018

Kerrレンズモード同期Yb:Lu2O3セラミック薄ディスクレーザー
北島将太朗; 白川晃; 八木秀喜; 柳谷高公
Poster presentation, Japanese, 第18回レーザー学会東京支部研究会, レーザー学会東京支部, 東海大学湘南キャンパス, Domestic conference
02 Mar. 2018

マルチコアフォトニック結晶ファイバーレーザーの選択的モード励振および モード解析
梯太郎; 黒須雄太; Henrik Tünnerman; 白川晃
Poster presentation, Japanese, 第18回レーザー学会東京支部研究会, レーザー学会東京支部, 東海大学湘南キャンパス, Domestic conference
02 Mar. 2018

音響光学変調器を用いたファイバーレーザーの能動モード同期
成富未夢人; 白川晃
Poster presentation, Japanese, 第18回レーザー学会東京支部研究会, レーザー学会東京支部, 東海大学湘南キャンパス, Domestic conference
02 Mar. 2018

新材料研究のための波長可変チタンサファイアレーザーの開発
小林祐樹; 白川晃
Poster presentation, Japanese, 第18回レーザー学会東京支部研究会, レーザー学会東京支部, 東海大学湘南キャンパス, Domestic conference
02 Mar. 2018

ファイバーレーザの高出力化のためのコヒーレントビーム結合
白川晃
Invited oral presentation, Japanese, レーザ協会第 180 回研究会, Invited, レーザ協会, 調布, Domestic conference
08 Feb. 2018

Coherent Pulse Stacking
チュナマン・ヘンリク; 白川晃
Invited oral presentation, English, レーザー学会学術講演会第38回年次大会, Invited, レーザー学会, 京都, Domestic conference
26 Jan. 2018

Kerrレンズモード同期Yb：Lu2O3セラミック薄ディスクレーザー
北島将太朗; 白川晃; 八木秀喜; 柳谷高公
Oral presentation, Japanese, レーザー学会学術講演会第38回年次大会, レーザー学会, 京都, Domestic conference
24 Jan. 2018

Phase Control in Temporal Coherent Beam Combining
Henrik Tünnermann; Akira Shirakawa
Poster presentation, English, 第10回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム, 文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」, 京都, Domestic conference
23 Jan. 2018

モード同期Yb:Lu2O3セラミックThin-diskレーザー
北島将太朗; 白川晃; 八木秀喜; 柳谷高公
Poster presentation, Japanese, 第10回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム, 文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」, 京都, Domestic conference
23 Jan. 2018

可飽和吸収体を用いたマルチコアファイバーレーザーのin-phaseモードパルス動作
八木澤大希; 白川晃
Poster presentation, Japanese, 第10回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム, 文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」, 京都, Domestic conference
23 Jan. 2018

Gain saturation in divided pulse amplification
Ei Jo; Henrik Tünnermann; Akira Shirakawa
Poster presentation, English, 第10回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム, 文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」, 京都, Domestic conference
23 Jan. 2018

CW and mode-locked high power Yb:Lu2O3 ceramic laser
S. Kitajima; A. Shirakawa; H. Yagi; T. Yanagitani
Invited oral presentation, English, 13th Laser Ceramics Symposium (LCS 2017), Invited, 13th Laser Ceramics Symposium (LCS 2017), Fryazino, Russia, International conference
06 Dec. 2017

Yb:Lu2O3セラミックを用いた高出力超短パルスレーザーの開発
北島将太朗; 白川晃; 八木秀喜; 柳谷高公
Oral presentation, Japanese, 超高速光エレクトロニクス（UFO）研究会第3回研究会, 超高速光エレクトロニクス（UFO）研究会, 調布, Domestic conference
17 Nov. 2017

Error Signal Generation for Coherent Combining using Bayesian Filters
Henrik Tünnermann; Akira Shirakawa
Oral presentation, English, レーザー学会第511回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, 名古屋, Domestic conference
10 Nov. 2017

Nonlinear effects in divided pulse amplification
Ei Jo; Koji Iwata; Henrik Tünnermann; Akira Shirakawa
Poster presentation, English, レーザー学会第511回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, 名古屋, Domestic conference
10 Nov. 2017

Design for evanescently-coupled multicore fiber laser beyond self-focusing limit
A. Shirakawa; H. Tünnermann
Poster presentation, English, International Conference on Extremely Light (ICEL) 2017, ELI, Szeged, Hungary, International conference
08 Nov. 2017

SRS-suppressed photonic bandgap fiber amplifier
D. Yagisawa; A. Shirakawa
Poster presentation, English, Advanced Solid-State Lasers (ASSL) 2017, Optical Society of America, Nagoya, Japan, International conference
02 Oct. 2017

CW performance and temperature observation of Yb:Lu2O3 ceramic thin-disk laser
S. Kitajima; H. Nakao; A. Shirakawa; H. Yagi; T. Yanagitani
Poster presentation, English, Advanced Solid-State Lasers (ASSL) 2017, Optical Society of America, Nagoya, Japan, International conference
02 Oct. 2017

Yb3+-doped CaF2-LaF3 ceramics for high power ultrashort pulse lasers
A. Shirakawa; S. Kitajima; K. Yamakado; K. Ueda; H. Ishizawa
Invited oral presentation, English, The 25th International Conference on Advanced Laser Technologies (ALT’17), Invited, The 25th International Conference on Advanced Laser Technologies (ALT’17), Busan, Korea, International conference
14 Sep. 2017

Yb:Lu2O3セラミック薄ディスクレーザ
北島将太朗; 中尾博明; 白川晃; 八木秀喜; 柳谷高公
Oral presentation, Japanese, 第78回応用物理学会秋季学術講演会, 応用物理学会, 福岡, Domestic conference
05 Sep. 2017

エバネッセント結合マルチコアファイバの位相同期レーザ動作
白川晃
Invited oral presentation, Japanese, 光通信インフラの飛躍的な高度化に関する時限研究専門委員会（EXAT）研究会, Invited, 光通信インフラの飛躍的な高度化に関する時限研究専門委員会（EXAT）, 札幌, Domestic conference
31 Aug. 2017

Mode-locked Yb:Lu2O3 ceramic laser at two different wavelengths
S. Kitajima; T. Matsumoto; A. Shirakawa; H. Yagi; T. Yanagitani
Oral presentation, English, The 24th Congress of the International Commission for Optics (ICO-24), The 24th Congress of the International Commission for Optics (ICO-24), Tokyo, Japan, International conference
24 Aug. 2017

1120 nm high-power ytterbium-Raman fiber source
A. Shirakawa; Y. Michibata
Oral presentation, English, The 24th Congress of the International Commission for Optics (ICO-24), The 24th Congress of the International Commission for Optics (ICO-24), Tokyo, Japan, International conference
22 Aug. 2017

Coherent pulse stacking with delay lines
H. Tünnermann; A. Shirakawa
Oral presentation, English, CLEO-PR, OECC & PGC 2017, CLEO-PR, OECC & PGC 2017, Singapore, International conference
01 Aug. 2017

Delay line coherent pulse stacking of a symmetric mode-locked pulse train
H. Tünnermann; A. Shirakawa
Oral presentation, English, CLEO-Europe/EQEC 2017, CLEO-Europe/EQEC 2017, Munich, Germany, International conference
26 Jun. 2017

Mode analysis in phase-locked multi-core photonic crystal fiber laser by interference method
Y. Kurosu; H. Tünnermann; A. Shirakawa
Poster presentation, English, CLEO-Europe/EQEC 2017, CLEO-Europe/EQEC 2017, Munich, Germany, International conference
26 Jun. 2017

Femtosecond mode-locked Yb3+-doped CaF2-LaF3 ceramic laser
S. Kitajima; A. Shirakawa; K. Ueda; H. Ishizawa
Oral presentation, English, CLEO-Europe/EQEC 2017, CLEO-Europe/EQEC 2017, Munich, Germany, International conference
26 Jun. 2017

Yb3+-doped CaF2-LaF3 ceramics for high power ultrashort pulse lasers
A. Shirakawa; S. Kitajima; K. Ueda; H. Ishizawa
Invited oral presentation, English, The 12th Pacific Rim Conference on Ceramic and Glass Techonology (PACRIM 12), Invited, The 12th Pacific Rim Conference on Ceramic and Glass Techonology (PACRIM 12), Waikoloa, Hawaii, USA, International conference
22 May 2017

Single-walled carbon nanotube mode-locked Yb3+-doped CaF2 laser
N.Yokoshima; S. Kitajima; A. Shirakawa; S. Y. Choi; F. Rotermund
Poster presentation, English, CLEO 2017, CLEO 2017, San Jose, USA, International conference
18 May 2017

Phase and combining efficiency in divided pulse amplification
K. Iwata; E. Jo; H.Tünnermann; A. Shirakawa
Oral presentation, English, CLEO 2017, CLEO 2017, San Jose, USA, International conference
18 May 2017

SRS-suppressed photonic bandgap fiber amplifier using a laser diode as the seed source
D. Yagisawa; A. Shirakawa
Oral presentation, English, 6th Advanced Lasers and Photon Sources (ALPS '17), 6th Advanced Lasers and Photon Sources (ALPS '17), Yokohama, Japan, International conference
18 Apr. 2017

Combining efficiny in divied pulse amplification
E. Jo; K. Iwata; H. Tünnermann; A. Shirakawa
Oral presentation, English, 6th Advanced Lasers and Photon Sources (ALPS '17), 6th Advanced Lasers and Photon Sources (ALPS '17), Yokohama, Japan, International conference
18 Apr. 2017

Sub-100 fs mode-locked Yb3+-doped CaF2 laser using single-walled carbon nanotube
N. Yokoshima; S. Kitajima; A. Shirakawa; S. Y. Choi; F. Rotermund
Oral presentation, English, 6th Advanced Lasers and Photon Sources (ALPS '17), 6th Advanced Lasers and Photon Sources (ALPS '17), Yokohama, Japan, International conference
18 Apr. 2017

Yb-doped CaF2-LaF3 ceramic laser
K. Yamakado; S. Kitajima; A. Shirakawa; K. Ueda; H. Ishizawa
Oral presentation, English, 6th Advanced Lasers and Photon Sources (ALPS '17), 6th Advanced Lasers and Photon Sources (ALPS '17), Yokohama, Japan, International conference
18 Apr. 2017

1120 nm high-power fiber source for 1178 nm fiber Raman amplifier pumping
Y. Michibata; A. Shirakawa
Poster presentation, English, 6th Advanced Lasers and Photon Sources (ALPS '17), 6th Advanced Lasers and Photon Sources (ALPS '17), Yokohama, Japan, International conference
18 Apr. 2017

半導体レーザーをシード源とした誘導ラマン散乱抑制フォトニックバンドギャップファイバー増幅器の開発
八木澤大希; 白川晃
Oral presentation, Japanese, 第64回応用物理学会春季学術講演会, 応用物理学会, パシフィコ横浜, Domestic conference
15 Mar. 2017

可飽和吸収体による受動Qスイッチ位相同期マルチコアファイバーレーザー
内部優花; 黒須雄太; 白川晃
Poster presentation, Japanese, 第64回応用物理学会春季学術講演会, 応用物理学会, パシフィコ横浜, Domestic conference
15 Mar. 2017

位相同期マルチコアファイバーレーザーの干渉法によるモード解析
黒須雄太; Henrik Tünnerman; 白川晃
Keynote oral presentation, Japanese, 第64回応用物理学会春季学術講演会, 応用物理学会, パシフィコ横浜, Domestic conference
15 Mar. 2017

カーボンナノチューブ可飽和吸収体を用いたモード同期Yb3+:CaF2レーザーの開発
横島直行; 北島将太朗; 白川晃; Sunyoung Choi; Fabian Rotermund
Oral presentation, Japanese, 第64回応用物理学会春季学術講演会, 応用物理学会, パシフィコ横浜, Domestic conference
15 Mar. 2017

半導体レーザーをシード源とした誘導ラマン散乱抑制フォトニックバンドギャップファイバー増幅器の開発
八木澤大希; 白川晃
Poster presentation, Japanese, 第17回レーザー学会東京支部研究会, レーザー学会東京支部, 東海大高輪キャンパス, Domestic conference
07 Mar. 2017

Yb添加Lu2O3セラミックレーザー
松本昂; 北島将太朗; 白川晃; 八木秀喜; 柳谷高公
Poster presentation, Japanese, 第17回レーザー学会東京支部研究会, レーザー学会東京支部, 東海大高輪キャンパス, Domestic conference
07 Mar. 2017

可飽和吸収体による受動Qスイッチ位相同期マルチコアファイバーレーザー
内部優花; 黒須雄太; 白川晃
Poster presentation, Japanese, 第17回レーザー学会東京支部研究会, レーザー学会東京支部, 東海大高輪キャンパス, Domestic conference
07 Mar. 2017

Yb添加CaF2-LaF3セラミックレーザー
山角謙太郎; 北島将太朗; 白川晃; 石沢均
Poster presentation, Japanese, 第17回レーザー学会東京支部研究会, レーザー学会東京支部, 東海大高輪キャンパス, Domestic conference
07 Mar. 2017

Ultrashort pulse laser based on new ceramic materials
S. Kitajima; A. Shirakawa
Poster presentation, English, CIAiS International Symposium 2017, Research and Education Consortium for Innovation of Advanced Integrated Science, Tokyo, Japan, International conference
27 Feb. 2017

Coherent pulse stacking with delay lines
Henrik Tünnermann; Akira Shirakawa
Oral presentation, English, Photonics West/LASE 2017, SPIE, San Francisco, USA, International conference
30 Jan. 2017

Temporal Beam Combining
Henrik Tuennermann; Koji Iwata; Ei Jo; Akira Shirakawa
Poster presentation, English, 第9回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム, Invited, 文部科学省、電気通信大学、大阪大学、東京大学, 東京, Domestic conference
24 Jan. 2017

セラミック新材料を用いた高出力超短パルスレーザーの研究
北島将太朗; 横島直行; 白川晃; 植田憲一
Poster presentation, Japanese, 第9回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム, Invited, 文部科学省、電気通信大学、大阪大学、東京大学, 東京, Domestic conference
24 Jan. 2017

半導体レーザーをシード源とした誘導ラマン散乱抑制フォトニックバンドギャップファイバー増幅
八木澤大希; 白川晃
Poster presentation, Japanese, 第9回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム, Invited, 文部科学省、電気通信大学、大阪大学、東京大学, 東京, Domestic conference
24 Jan. 2017

Yb添加CaF2-LaF3セラミックレーザー
山角謙太郎; 北島将太郎; 白川晃; 石沢 均
Poster presentation, Japanese, 第9回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム, Invited, 文部科学省、電気通信大学、大阪大学、東京大学, 東京, Domestic conference
24 Jan. 2017

Ultrashort pulse laser based on new ceramic materials
S. Kitajima; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; H. Ishizawa
Oral presentation, English, Photonics and Laser Technology Symposium, Univ. Electro-Commun., Chofu, Japan, International conference
20 Jan. 2017

半導体レーザーをシード源とした誘導ラマン散乱抑制フォトニックバンドギャップファイバー増幅
八木澤大希; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第37回年次大会, レーザー学会, 名古屋, Domestic conference
09 Jan. 2017

位相同期マルチコアファイバ－レーザーの干渉法によるモード計測
黒須雄太; Henrik Tünnermann; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第37回年次大会, レーザー学会, 名古屋, Domestic conference
09 Jan. 2017

分割パルス増幅における位相と結合効率
岩田興治; チュナマン・ヘンリク; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第37回年次大会, レーザー学会, 名古屋, Domestic conference
09 Jan. 2017

Coherent pulse stacking for fiber amplifier energy scaling
Henrik Tuennermann; 白川晃
Oral presentation, English, レーザー学会学術講演会第37回年次大会, レーザー学会, 名古屋, Domestic conference
09 Jan. 2017

Yb添加CaF2-LaF3セラミックレーザーのイオン添加濃度依存性
山角謙太郎; 北島将太郎; 白川晃; 江面嘉信; 石沢 均
Oral presentation, Japanese, レーザー学会学術講演会第37回年次大会, レーザー学会, 名古屋, Domestic conference
08 Jan. 2017

カーボンナノチューブ可飽和吸収体を用いたYb3+:CaF2モード同期レーザーの開発
横島直行; 北島将太朗; 白川晃; Sunyoung Choi; Fabian Rotermund
Oral presentation, Japanese, レーザー学会学術講演会第37回年次大会, レーザー学会, 名古屋, Domestic conference
07 Jan. 2017

サブ100 fs カーレンズモード同期Yb3+:Lu3Al5O12セラミックレーザー
北島将太朗; 白川晃; 八木秀喜; 柳谷高公
Oral presentation, Japanese, レーザー学会学術講演会第37回年次大会, レーザー学会, 名古屋, Domestic conference
07 Jan. 2017

Sub-100 fs Kerr-lens mode-locked Yb3+-doped Lu3Al5O12 ceramic laser
S. Kitajima; A. Shirakawa; H. Yagi; T. Yanagitani
Oral presentation, English, 12th Laser Ceramics Symposium (LCS 2016), 12th Laser Ceramics Symposium (LCS 2016), Saint-Louis, France, International conference
29 Nov. 2016

Yb3+-doped CaF2-LaF3 ceramics for high power ultrashort pulse lasers
A. Shirakawa; S. Kitajima; K. Ueda; Y. Ezura; H. Ishizawa
Invited oral presentation, English, 12th Laser Ceramics Symposium (LCS 2016), Invited, 12th Laser Ceramics Symposium (LCS 2016), Saint-Louis, France, International conference
29 Nov. 2016

分割パルスファイバー増幅における位相と結合効率
岩田興治; チュナマン・ヘンリク; 白川晃
Oral presentation, Japanese, レーザー学会第496回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, 名古屋, Domestic conference
18 Nov. 2016

半導体レーザーをシード源とした誘導ラマン散乱抑制フォトニックバンドギャップファイバー増幅
八木澤大希; 白川晃
Poster presentation, Japanese, レーザー学会第496回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, 名古屋, Domestic conference
18 Nov. 2016

位相同期マルチコアファイバ－レーザーの干渉法によるモード計測
黒須雄太; Henrik Tünnermann; 白川晃
Poster presentation, Japanese, レーザー学会第496回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, 名古屋, Domestic conference
18 Nov. 2016

Novel Material Ceramics for Femtosecond Lasers
A. Shirakawa; S. Kitajima; K. Ueda
Invited oral presentation, English, Materials Science & Technology 2016 (MS & T16), Invited, MS & T16, Salt Lake City, USA, International conference
26 Oct. 2016

Phase-locked multicore fiber lasers
A. Shirakawa; T. Kubouchi; Y. Kurosu; H. Tünnermann
Invited oral presentation, English, 21st International Symposium on High Power Laser Systems and Applications (HPLS&A 2016), Invited, HPLS&A 2016, Gmunden, Austria, International conference
05 Sep. 2016

Sub-100 fs Kerr-lens mode-locked Yb3+-doped Lu3Al5O12 ceramic laser
S. Kitajima; H. Nakao; A. Shirakawa; H. Yagi; T. Yanagitani
Oral presentation, English, 7th EPS-QEOD Europhoton Conference, 7th EPS-QEOD Europhoton Conference, Vienna, Austria, International conference
26 Aug. 2016

Pulse Energy Scaling by Delay Line Stacking
Henrik Tünnermann; Akira Shirakawa
Oral presentation, English, レーザー学会ファイバーレーザー技術専門委員会第5回委員会, レーザー学会ファイバーレーザー技術専門委員会, 東京, Domestic conference
29 Jul. 2016

Delay Line Coherent Pulse Stacking
H. Tuennermann; A. Shirakawa
Oral presentation, English, CLEO 2016, CLEO 2016, San Jose, USA, International conference
06 Jun. 2016

Highly Efficient Yb3+-doped CaF2-LaF3 Ceramic Laser
S. Kitajima; Y. Higashi; H. Nakao; A. Shirakawa; K. Ueda; Y. Ezura; H. Ishizawa
Oral presentation, English, CLEO 2016, CLEO 2016, San Jose, USA, International conference
06 Jun. 2016

Divided Pulse Amplification: Spectral Phase and Combining Efficiency
K. Iwata; H. Tuennermann; A. Shirakawa
Oral presentation, English, 5th Advanced Lasers and Photon Sources (ALPS '16), 5th Advanced Lasers and Photon Sources (ALPS '16), Yokohama, Japan, International conference
17 May 2016

Phase-locked 7-core multi-core photonic crystal fiber laser
Y. Kurosu; T. Kubouchi; H. Tuennermann; A. Shirakawa
Oral presentation, English, 5th Advanced Lasers and Photon Sources (ALPS '16), 5th Advanced Lasers and Photon Sources (ALPS '16), Yokohama, Japan, International conference
17 May 2016

分割パルスファイバー増幅器の開発
岩田興治; チュナマン・ヘンリク; 白川晃
Oral presentation, Japanese, 第63回応用物理学会春季学術講演会, 第63回応用物理学会春季学術講演会, 東京, Domestic conference
20 Mar. 2016

ファイバーラマン増幅器励起用高出力 1120 nmファイバー光源の開発
道端優; 陳明晨; 白川晃
Oral presentation, Japanese, 第63回応用物理学会春季学術講演会, 第63回応用物理学会春季学術講演会, 東京, Domestic conference
20 Mar. 2016

次世代ファイバーレーザー：フォトニックバンドギャップファイバーレーザー及びマルチコアファイバーレーザー
白川晃
Invited oral presentation, Japanese, 豊田工業大学第16回先端フォトンテクノロジー研究センターシンポジウム, Invited, 豊田工業大学, 名古屋, Domestic conference
04 Mar. 2016

Yb3+添加CaF2-LaF3セラミックレーザー
北島将太朗; 東祐軌; 中尾博明; 白川晃; 植田憲一; 江面嘉信; 石沢均
Oral presentation, Japanese, レーザー学会学術講演会第36回年次大会, レーザー学会, 名古屋, Domestic conference
10 Jan. 2016

位相同期Yb添加7コアマルチコアフォトニック結晶ファイバーレーザー
黒須雄太; 久保内照雄; Henrik Tunnermann; 白川晃; 齋藤和也
Oral presentation, Japanese, レーザー学会学術講演会第36回年次大会, レーザー学会, 名古屋, Domestic conference
09 Jan. 2016

可飽和吸収体Qスイッチ位相同期マルチコアファイバーレーザーのサイドローブ抑制
久保内照雄; 黒須雄太; チュナマン・ヘンリク; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第36回年次大会, レーザー学会, 名古屋, Domestic conference
09 Jan. 2016

Yb3+-doped CaF2-LaF3 Ceramic Laser
S. Kitajima; Y. Higashi; H. Nakao; A. Shirakawa; K. Ueda; Y. Ezura; H. Ishizawa
Oral presentation, English, 11th Laser Ceramics Symposium (LCS 2015), LCS 2015, Xuzhou, China, International conference
04 Dec. 2015

Novel Material Ceramics Lasers
Akira Shirakawa
Invited oral presentation, English, 11th Laser Ceramics Symposium (LCS 2015), Invited, LCS 2015, Xuzhou, China, International conference
01 Dec. 2015

可飽和吸収体を用いたQスイッチ位相同期マルチコアファイバーレーザー
久保内照雄; 黒須雄太; 佐藤慶吾; チュナマン・ヘンリク; 白川晃
Oral presentation, Japanese, レーザー学会第482回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, 名古屋, Domestic conference
27 Nov. 2015

位相同期Yb添加7コアマルチコアフォトニック結晶ファイバーレーザー
黒須雄太; 久保内照雄; Henrik Tünnermann; 白川晃; 齋藤和也
Poster presentation, Japanese, レーザー学会第482回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, 名古屋, Domestic conference
27 Nov. 2015

分割パルスファイバー増幅器の開発
岩田興治; チュナマン・ヘンリク; 白川晃
Poster presentation, Japanese, レーザー学会第482回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, 名古屋, Domestic conference
27 Nov. 2015

ファイバーラマン増幅器励起用高出力 1120 nmファイバー光源の開発
道端優; 陳明晨; 白川晃
Poster presentation, Japanese, レーザー学会第482回研究会「ファイバーレーザー技術」, レーザー学会ファイバーレーザー技術研究会, 名古屋, Domestic conference
27 Nov. 2015

7コアマルチコアフォトニック結晶ファイバーレーザーの位相同期特性
黒須雄太; 久保内照雄; 佐藤慶吾; 白川 晃; 小森翼; 齋藤和也
Oral presentation, Japanese, 第76回応用物理学会学術講演会, 応用物理学会, 名古屋, Domestic conference
13 Sep. 2015

サイドローブ抑制可飽和吸収体位相同期マルチコアファイバーレーザー
久保内照雄; 白川 晃
Oral presentation, Japanese, 第76回応用物理学会学術講演会, 応用物理学会, 名古屋, Domestic conference
13 Sep. 2015

Coupled multicore fibers in the high power regime: Impact of core size mismatch
H. Tünnermann; A. Shirakawa
Oral presentation, English, CLEO-PR 2015, CLEO-PR 2015, Busan, Korea, International conference
28 Aug. 2015

Spectrally-filtering photonic bandgap fiber lasers
Akira Shirakawa
Invited oral presentation, English, OECC 2015, Invited, OECC 2015, Shanghai, China, International conference
Jul. 2015

Power scaling with coupled multi-core fibers
H. Tünnermann; A. Shirakawa
Invited oral presentation, English, ICMAT15 (International Conference on Materials for Advanced Technologies), Invited, ICMAT15, Singapore, International conference
Jul. 2015

Impact of different order photonic bandgap in spectral filtering photonic bandgap fiber amplifier
M. Chen; S. R. Petersen; C. B. Olausson; T. T. Alkeskjold; A. Shirakawa
Oral presentation, English, CLEO/Europe 2015, CLEO/Europe 2015, Munich, Germany, International conference
24 Jun. 2015

Kerr-lens mode-locked Yb3+-doped Lu3Al5O12 ceramic laser
S. Kitajima; H. Nakao; A. Shirakawa; H. Yagi; T. Yanagitani
Oral presentation, English, CLEO/Europe 2015, CLEO/Europe 2015, Munich, Germany, International conference
21 Jun. 2015

Sub-200 fs mode-locked Nd3+-doped Ba(Zr,Mg,Ta)O3 ceramic laser
Y. Higashi; A. Shirakawa; K. Ueda; A. A. Kaminskii; S. Kuretake; Y. Kintaka; K. Murayama; N. Tanaka
Oral presentation, English, CLEO/Europe 2015, CLEO/Europe 2015, Munich, Germany, International conference
21 Jun. 2015

Kerr-lens mode-locked Yb3+-doped Lu3Al5O12 ceramic laser
S. Kitajima; H. Nakao; A. Shirakawa; H. Yagi; T. Yanagitani
Oral presentation, English, 4th Advanced Lasers and Photon Sources (ALPS '15), 4th Advanced Lasers and Photon Sources (ALPS '15), Yokohama, Japan, International conference
24 Apr. 2015

Impact of different order photonic bandgap in spectral filtering photonic bandgap fiber amplifier
M. Chen; S. R. Petersen; C. B. Olausson; T. T. Alkeskjold; A. Shirakawa
Oral presentation, English, 4th Advanced Lasers and Photon Sources (ALPS '15), 4th Advanced Lasers and Photon Sources (ALPS '15), Yokohama, Japan, International conference
24 Apr. 2015

サイドローブ抑制可飽和吸収体位相同期マルチコアファイバーレーザー
久保内照雄; 佐藤慶吾; 白川晃
Oral presentation, Japanese, 第15回レーザー学会東京支部研究会, レーザー学会東京支部, 東海大高輪キャンパス, Domestic conference
05 Mar. 2015

Kerrレンズモード同期Yb3+添加Lu3Al5O12セラミックレーザー
北島将太朗; 中尾博明; 白川晃; 八木秀喜; 柳谷高公
Oral presentation, Japanese, 第15回レーザー学会東京支部研究会, レーザー学会東京支部, 東海大高輪キャンパス, Domestic conference
05 Mar. 2015

7コアフォトニック結晶ファイバーレーザーの位相同期特性
黒須雄太; 久保内照雄; 佐藤慶吾; 白川晃; 小森翼; 齋藤和也
Oral presentation, Japanese, 第15回レーザー学会東京支部研究会, レーザー学会東京支部, 東海大高輪キャンパス, Domestic conference
05 Mar. 2015

Spectral analysis of SRS suppression in photonic bandgap fibers
M. Karow; Y. Suzuki; H. Tünnermann; A. Shirakawa
Oral presentation, English, Photonics West/LASE 2015, SPIE, San Francisco, USA, International conference
10 Feb. 2015

Impact of coupling strength on self-focusing in multicore fibers
H. Tünnermann; A. Shirakawa
Oral presentation, English, Photonics West/LASE 2015, SPIE, San Francisco, USA, International conference
10 Feb. 2015

High-power single-frequency fiber MOPA at 1178 nm
M. Chen; A. Shirakawa; C. B. Olausson; T. T. Alkeskjold
Oral presentation, English, Photonics West/LASE 2015, SPIE, San Francisco, USA, International conference
09 Feb. 2015

可飽和吸収体によるQスイッチ位相同期マルチコアファイバーレーザーの高エネルギー化
久保内照雄; 佐藤慶吾; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第35回年次大会, レーザー学会, 東海大高輪キャンパス, Domestic conference
12 Jan. 2015

有限要素法を用いたフォトニックバンドギャップファイバー伝搬モードの損失解析
陳明晨; 白川晃
Oral presentation, Japanese, レーザー学会学術講演会第35回年次大会, レーザー学会, 東海大高輪キャンパス, Domestic conference
12 Jan. 2015

モード同期Nd3+添加Ba(Zr,Mg,Ta)O3セラミックレーザー
東祐軌; 中尾博明; 白川晃; 植田憲一; 呉竹悟志; 金高祐仁; 村山浩二; 田中伸彦; Alexander A. Kaminskii
Oral presentation, Japanese, レーザー学会学術講演会第35回年次大会, レーザー学会, 東海大高輪キャンパス, Domestic conference
12 Jan. 2015

Kerrレンズモード同期Yb3+添加Lu3Al5O12セラミックレーザー
北島将太朗; 中尾博明; 白川晃; 八木秀喜; 柳谷高公
Oral presentation, Japanese, レーザー学会学術講演会第35回年次大会, レーザー学会, 東海大高輪キャンパス, Domestic conference
12 Jan. 2015

Mitigation of the self-focusing limit via multicore fiber
Henrik Tünnermann; Akira Shirakawa
Oral presentation, English, レーザー学会ファイバーレーザー技術専門委員会第3回公開研究会, レーザー学会ファイバーレーザー技術専門委員会, 名古屋, Domestic conference
28 Nov. 2014

可飽和吸収体によるQスイッチ位相同期マルチコアファイバーレーザーの高出力化
久保内照雄; 佐藤慶吾; 白川晃
Oral presentation, Japanese, レーザー学会ファイバーレーザー技術専門委員会第3回公開研究会, レーザー学会ファイバーレーザー技術専門委員会, 名古屋, Domestic conference
28 Nov. 2014

高出力単一周波数1178nmファイバーMOPA
陳明晨; 白川晃; C. B; Olausson,T. T. Alkeskjold
Oral presentation, Japanese, レーザー学会ファイバーレーザー技術専門委員会第3回公開研究会, レーザー学会ファイバーレーザー技術専門委員会, 名古屋, Domestic conference
28 Nov. 2014

All normal fiber oscillator for investigation of divided pulse amplification
Henrik Tünnermann; Akira Shirakawa
Oral presentation, English, レーザー学会ファイバーレーザー技術専門委員会第3回公開研究会, レーザー学会ファイバーレーザー技術専門委員会, 名古屋, Domestic conference
28 Nov. 2014

Self-focusing in multicore fibers
H. Tünnermann; A. Shirakawa
Oral presentation, English, Advanced Solid-State Lasers (ASSL) 2014, Optical Society of America, Shanghai, China, International conference
18 Nov. 2014

Femtosecond mode-locked Nd3+-doped Ba(Zr,Mg,Ta)O3 ceramic laser
Y. Higashi; H. Nakao; A. Shirakawa; K. Ueda; A. A. Kaminskii; S. Kuretake; Y. Kintaka; K. Murayama; N. Tanaka
Oral presentation, English, Advanced Solid-State Lasers (ASSL) 2014, Optical Society of America, Shanghai, China, International conference
17 Nov. 2014

High-power single-frequency fiber MOPA based on FRA and PBGF amplifier at 1178 nm
M. Chen; A. Shirakawa; C. B. Olausson; T. T. Alkeskjold
Oral presentation, English, Advanced Solid-State Lasers (ASSL) 2014, Optical Society of America, Shanghai, China, International conference
17 Nov. 2014

Phase-locked multicore fiber lasers for power and energy scaling
Akira Shirakawa
Keynote oral presentation, English, The Second International Seminar on High-power Laser Interaction with Matter and Application, Invited, Chinese Society of Astronautics, Suzhou, China, International conference
Oct. 2014

Photonic bandgap fiber laser for sodium guide star applications
Akira Shirakawa
Invited oral presentation, English, Frontiers in Optics 2014, Invited, Optical Society of America, Tucson, USA, International conference
Oct. 2014

モード同期Yb3+添加Lu 3Al5O12セラミックレーザー
北島将太朗; 中尾博明; 白川晃; 八木秀喜; 柳谷高公
Oral presentation, Japanese, 第75回応用物理学会学術講演会, 応用物理学会, 札幌・北海道大学, Domestic conference
20 Sep. 2014

高出力・高効率Yb:LuAG セラミックthin-disk レーザー
中尾博明; 白川晃; 植田憲一; 八木秀喜; 柳谷高公; Birgit Weichelt; Katrin Wentsch,Marwan Abdou Ahmed; Thomas Graf
Oral presentation, Japanese, 第75回応用物理学会学術講演会, 応用物理学会, 札幌・北海道大学, Domestic conference
20 Sep. 2014

フェムト秒モード同期Nd3+添加Ba(Zr,Mg,Ta)O3セラミックレーザー
東祐軌; 富田貴之; 布施純一; 中尾博明; 白川晃; 植田憲一; 呉竹悟志; 金高祐二; 村山浩二; 田中伸彦; Alexander A. Kaminskii
Oral presentation, Japanese, 第75回応用物理学会学術講演会, 応用物理学会, 札幌・北海道大学, Domestic conference
20 Sep. 2014

Self Focusing in Multicore Fiber Designs
Henrik Tuennermann; Akira Shirakawa
Oral presentation, English, 第75回応用物理学会学術講演会, 応用物理学会, 札幌・北海道大学, Domestic conference
19 Sep. 2014

張力分布によるファイバーラマン増幅器での誘導ブリルアン散乱の抑制
陳明晨; 鈴木悠太; 白川晃
Oral presentation, Japanese, 第75回応用物理学会学術講演会, 応用物理学会, 札幌・北海道大学, Domestic conference
19 Sep. 2014

CLEO 2014会議報告
白川晃
Others, Japanese, レーザー学会ファイバーレーザー技術委員会第8回委員会, Invited, レーザー学会ファイバーレーザー技術専門委員会, 柏（東京大学物性研究所）, Domestic conference
22 Aug. 2014

Phase-locked multicore fiber lasers
Akira Shirakawa
Invited oral presentation, English, CLEO 2014, Invited, Optical Society of America, San Jose, USA, International conference
Jun. 2014

Ceramic thin-disk lasers
H. Nakao; T. Inagaki; M. Tokurakawa; A. Shirakawa; K. Ueda; A. A. Kaminskii; H. Yagi; T. Yanagitani; B. Weichelt; K. Wentsch; M. Abdou Ahmed; T. Graf
Invited oral presentation, English, Stuttgart Laser Technology Forum (SLT 2014), Invited, Institut für Strahlwerkzeuge (IFSW), Universität Stuttgart, Stuttgart, Germany, International conference
Jun. 2014

Photonic bandgap fiber lasers and multicore fiber lasers for next generation high power lasers
A. Shirakawa; M. Chen; Y. Suzuki; K. Sato; X. Fan; H. Tünnermann; M. Karow; C. B. Olausson; S. R. Petersen; T. Alkeskjold; K. Saito
Invited oral presentation, English, Specialty Optical Fibers & Applications 2014, Invited, Optical Society of America, Barcelona, Spain, International conference
Jun. 2014

Photonics West 2014会議報告
白川晃
Others, Japanese, レーザー学会ファイバーレーザー技術委員会第7回委員会, Invited, レーザー学会ファイバーレーザー技術専門委員会, 吹田（大阪大学レーザーエネルギー学研究センター）, Domestic conference
23 May 2014

Photonic bandgap and multicore fiber lasers for next-generation lasers
Akira Shirakawa
Invited oral presentation, English, Advanced Lasers and Their Applications (ALTA) 2014, Invited, Optical Society of Korea, Jeju, Korea, International conference
May 2014

Yb3+-doped Lu2O3 ceramic thin-disk laser
H. Nakao; T. Inagaki; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani
Oral presentation, English, 3rd Advanced Lasers and Photon Sources (ALPS '14), 3rd Advanced Lasers and Photon Sources (ALPS '14), Yokohama, Japan, International conference
Apr. 2014

Femtosecond mode-locked Nd3+-doped Ba(Zr,Mg,Ta)O3 ceramic laser
Y. Higashi; T. Tomita; J. Fuse; H. Nakao; A. Shirakawa; K. Ueda; A. A. Kaminskii; S. Kuretake; Y. Kintaka; K. Murayama; N. Tanaka
Oral presentation, English, 3rd Advanced Lasers and Photon Sources (ALPS '14), 3rd Advanced Lasers and Photon Sources (ALPS '14), Yokohama, Japan, International conference
Apr. 2014

Phase-locked Q-switched multicore fiber laser with saturable absorber
K. Sato; T. Kubouchi; H.Yamada; A. Shirakawa
Oral presentation, English, 3rd Advanced Lasers and Photon Sources (ALPS '14), 3rd Advanced Lasers and Photon Sources (ALPS '14), Yokohama, Japan, International conference
Apr. 2014

Photonic bandgap and multicore fiber lasers for next-generation lasers
Akira Shirakawa
Invited oral presentation, English, UEC / IOP-VAST Workshop on Optical Science, Invited, University of Electro-Coomunications, Chofu, Japan, International conference
27 Mar. 2014

Single-frequency 1178 nm SDL/Yb-PBGF MOPA with an output power of 31 W
T. Leinonen; M. Chen; X. Fan; E. L. Kantola; A. Shirakawa; M. D. Guina
Oral presentation, English, Photonics West/LASE 2014, SPIE, International conference
Feb. 2014

Phase-locked, Q-switched multicore fiber laser by saturable absorber
A. Shirakawa; K. Sato; H. Yamada
Oral presentation, English, Photonics West/LASE 2014, SPIE, San Francisco, USA, International conference
Feb. 2014

LD励起Yb3+添加Lu2O3セラミックthin-diskレーザー
中尾博明; 稲垣達也; 白川晃; 植田憲一; 八木秀喜; 柳谷高公; A. A. Kaminskii
Oral presentation, Japanese, レーザー学会学術講演会第34回年次大会, レーザー学会, Domestic conference
Jan. 2014

誘導ラマン散乱抑制フォトニックバンドギャップファイバー増幅器の高尖頭出力化
鈴木悠太; 陳明晨; 白川晃; C. B. Olausson; J. Broeng
Oral presentation, Japanese, レーザー学会学術講演会第34回年次大会, レーザー学会, 北九州, Domestic conference
Jan. 2014

Ceramic thin-disk lasers of Yb3+:Lu3Al12O5 and Yb3+:Lu2O3
A. Shirakawa; H. Nakao; T. Inagaki; K. Ueda; H. Yagi; T. Yanagitani
Invited oral presentation, English, 9th Laser Ceramics Symposium, Invited, 9th Laser Ceramics Symposium, International conference
Dec. 2013

可飽和吸収体によるマルチコアファイバーレーザーの位相同期Qスイッチパルス発振
佐藤慶吾; 山田英典; 白川晃
Oral presentation, Japanese, レーザー学会ファイバーレーザー技術専門委員会公開研究会, レーザー学会ファイバーレーザー技術専門委員会, Domestic conference
22 Nov. 2013

位相変調サイドバンドを用いたPBGFのブリルアン利得スペクトル計測
陳明晨; 鈴木悠太; 白川晃; C. B. Olausson; J. Broeng
Oral presentation, Japanese, レーザー学会ファイバーレーザー技術専門委員会公開研究会, レーザー学会ファイバーレーザー技術専門委員会, Domestic conference
22 Nov. 2013

フォトニックバンドギャップファイバーによる誘導ラマン散乱抑制パルス増幅
鈴木悠太; 陳明晨; 白川晃; C. B. Olausson; J. Broeng
Oral presentation, Japanese, レーザー学会ファイバーレーザー技術専門委員会公開研究会, レーザー学会ファイバーレーザー技術専門委員会, 名古屋・名古屋大学, Domestic conference
22 Nov. 2013

Phase-locked multicore fiber lasers for power and energy scaling
Akira Shirakawa
Invited oral presentation, English, Asia Communications and Photonics Conference (ACP) 2013, Invited, Asia Communications and Photonics Conference (ACP) 2013, Beijing, China, International conference
Nov. 2013

Efficient High Power Operation of Yb3+-doped Lu3Al5O12 ceramic thin-disk laser
H. Nakao; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; B. Weichelt; K. Wentsch; M. Abdou Ahmed; T. Graf
Oral presentation, English, Advanced Solid-State Lasers (ASSL) 2013, Optical Society of America, International conference
Oct. 2013

Yb3+-doped CaF2-LaF3 Ceramic Laser
A. Shirakawa; H. Nakao; Y. Higashi; K. Ueda; Y. Ezura; H. Ishizawa
Oral presentation, English, Advanced Solid-State Lasers (ASSL) 2013, Optical Society of America, International conference
Oct. 2013

フォトニックバンドギャップファイバーによる誘導ラマン散乱抑制高尖頭出力パルス増幅
鈴木悠太; 有佐傑; 陳明晨; 白川晃; C. B. Olausson; J. Broeng
Oral presentation, Japanese, 第74回応用物理学会学術講演会, 応用物理学会, 京都・同志社大学, Domestic conference
Sep. 2013

可飽和吸収体を用いた位相同期Qスイッチマルチコアファイバーレーザー
佐藤慶吾; 山田英典; 白川晃
Oral presentation, Japanese, 第74回応用物理学会学術講演会, 応用物理学会, Domestic conference
Sep. 2013

100 W Yb3+添加Lu3Al5O12セラミックthin-disk レーザー
中尾博明; 白川晃; 植田憲一; 八木秀喜; 柳谷高公; B. Weichelt; K. Wentsch; M. Abdou Ahmed; T. Graf
Oral presentation, Japanese, 第74回応用物理学会学術講演会, 応用物理学会, Domestic conference
Sep. 2013

Yb3+添加Lu2O3 セラミック thin-disk レーザー
稲垣達也; 中尾博明; 白川晃; 植田憲一; 八木秀喜; 柳谷高公
Oral presentation, Japanese, 第74回応用物理学会学術講演会, 応用物理学会, Domestic conference
Sep. 2013

Nd3+添加Ba(Zr,Mg,Ta)O3セラミックレーザーの研究
東祐軌; 布施純一; 中尾博明; 白川晃; 植田憲一; 呉竹悟志; 田中伸彦; 金高祐二; 景山恵介; A. A. Kaminskii
Oral presentation, Japanese, 第74回応用物理学会学術講演会, 応用物理学会, Domestic conference
Sep. 2013

次世代レーザーを目指したフォトニックバンドギャップ・マルチコアファイバーレーザー
白川晃
Invited oral presentation, Japanese, 電気学会先端光・量子発生利用技術専門委員会第6回委員会, Invited, 電気学会先端光・量子発生利用技術専門委員会, 東京, Domestic conference
31 Jul. 2013

ファイバーレーザーの世界的研究の現状~高出力ファイバーレーザー~
白川晃
Others, Japanese, レーザー学会ファイバーレーザー技術専門委員会第5回委員会, Invited, レーザー学会ファイバーレーザー技術専門委員会, 調布（電気通信大学）, Domestic conference
19 Jul. 2013

CLEO 2013会議報告
白川晃
Others, Japanese, レーザー学会ファイバーレーザー技術専門委員会第5回委員会, Invited, レーザー学会ファイバーレーザー技術専門委員会, 調布（電気通信大学）, Domestic conference
19 Jul. 2013

High power 1178 nm single-frequency MOPA based on OP-SDL and PBGF
M. Chen; X. Fan; A. Shirakawa; T. Leinonen; E. Kantola; M. Guina; C. B. Olausson; J. Broeng
Oral presentation, English, CLEO-PR & OECC/PS 2013
Jul. 2013

98 W 1178 nm Yb-doped solid-core photonic bandgap fiber oscillator
X. Fan; M. Chen; A. Shirakawa; C. B. Olausson; J. Broeng
Oral presentation, English, CLEO-PR & OECC/PS 2013
Jul. 2013

High-peak power pulse amplification by SRS suppressed photonic bandgap fiber
A. Shirakawa; Y. Suzuki; S. Arisa; M. Chen; C. B. Olausson; J. K. Lyngsø J. Broeng
Oral presentation, English, CLEO-PR & OECC/PS 2013
Jul. 2013

Yb3+-doped Lu3Al5O12 ceramic thin-disk laser
H. Nakao; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; B. Weichelt; K. Wentsch; M. Abdou Ahmed; T. Graf
Oral presentation, English, CLEO-PR & OECC/PS 2013
Jul. 2013

Research and Development of fiber lasers -Photonic bandgap and multicore fiber lasers for next-generation high-power lasers
Akira Shirakawa
Invited oral presentation, English, 3rd UEC Symposium, Invited, University of Electro-Communications, Shenzhen, China, International conference
14 May 2013

Photonic bandgap and multicore fiber lasers for next-generation high-power lasers
Akira Shirakawa
Invited oral presentation, English, 2nd Advanced Lasers and Photon Sources (ALPS '13), Invited, 2nd Advanced Lasers and Photon Sources (ALPS '13), Yokohama, Japan, International conference
Apr. 2013

Qスイッチ位相同期マルチコアファイバーレーザー
佐藤慶吾; 山田英典; 白川晃; 植田憲一
Oral presentation, Japanese, 第13回レーザー学会東京支部研究会,第13回レーザー学会東京支部研究会
Mar. 2013

誘導ラマン散乱抑制フォトニックバンドギャップファイバーによる高尖頭出力パルス増幅
鈴木悠太; 有佐傑; 陳明晨; 山田英典; 白川晃; C. B. Olausson; J. Broeng
Oral presentation, Japanese, 第13回レーザー学会東京支部研究会,第13回レーザー学会東京支部研究会
Mar. 2013

高出力1178nmフォトニックバンドギャップファイバレーザー
白川晃; X. Fan; 陳明晨; 植田憲一; C. B. Olausson; J. K. Lyngsø J. Broeng
Oral presentation, Japanese, レーザー学会学術講演会第33回年次大会,レーザー学会学術講演会第33回年次大会
Jan. 2013

フォトニックバンドギャップファイバーを用いた誘導ラマン散乱抑制パルス増幅
鈴木悠太; 陳明晨; 山田英典; 白川晃; C. B. Olausson; J. Broeng
Oral presentation, Japanese, レーザー学会学術講演会第33回年次大会,レーザー学会学術講演会第33回年次大会
Jan. 2013

Yb:LuAGセラミックレーザーの開発
中尾博明; 白川晃; 植田憲一; 八木秀喜; 柳谷高公
Oral presentation, Japanese, 第5回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム,第5回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム
Jan. 2013

Qスイッチ位相同期マルチコアフォトニック結晶ファイバーレーザー
山田英典; 佐藤慶吾; 白川晃; 植田憲一
Oral presentation, Japanese, 第5回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム,第5回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム
Jan. 2013

Qスイッチ位相同期マルチコアファイバーレーザーの研究
佐藤慶吾; 山田英典; 白川晃; 植田憲一
Oral presentation, Japanese, 第9回ナノ未来材料とコヒーレント光科学合同シンポジウム,第9回ナノ未来材料とコヒーレント光科学合同シンポジウム
Dec. 2012

Single-frequency amplification by ytterbium-doped photonic bandgap fiber at 1178 nm
陳明晨; 白川晃; 植田憲一; C. B. Olausson; J. K. Lyngsø J. Broeng
Oral presentation, Japanese, 第9回ナノ未来材料とコヒーレント光科学合同シンポジウム,第9回ナノ未来材料とコヒーレント光科学合同シンポジウム
Dec. 2012

Ultrafast ceramic lasers
A. Shirakawa; M. Tokurakawa; H. Nakao; K. Ueda; A.A. Kaminskii
Invited oral presentation, English, 8th Laser Ceramics Symposium, 8th Laser Ceramics Symposium
Dec. 2012

高出力レーザー特論
白川晃
Public discourse, Japanese, 光産業技術振興協会レーザ安全スクール, Invited, 光産業技術振興協会
16 Nov. 2012

高出力単一周波数1178nmファイバー光源の開発
陳明晨; 白川晃; 植田憲一; C. B. Olausson; J. K. Lyngsø J. Broeng
Oral presentation, Japanese, レーザー学会「ファイバーレーザー技術専門委員会」公開研究会,「ファイバーレーザー技術専門委員会」公開研究会
Nov. 2012

Laser research at ILS/UEC –Photonic bandgap/Multicore fiber lasers and ultrafast ceramic lasers
Akira Shirakawa
Others, English, Special Seminar, Institut für Strahlwerkzeuge (IFSW), Universität Stuttgart
Oct. 2012

Laser research at ILS/UEC –Photonic bandgap/Multicore fiber lasers and ultrafast ceramic lasers
Akira Shirakawa
Others, English, Special Seminar, Institut für Strahlwerkzeuge (IFSW), Universität Stuttgart
Oct. 2012

Phase-locked multi-core photonic crystal fiber laser
H. Yamada; K. Sato; A. Shirakawa; K. Ueda
Oral presentation, English, International Workshop on Laser Science (IWLS)
Oct. 2012

Photonic bandgap fiber sources for next generation fiber lasers
X. Fan; M. Chen; Y. Suzuki; A. Shirakawa; K. Ueda; C. B. Olausson; J. K. Lyngsø J. Broeng
Oral presentation, English, International Workshop on Laser Science (IWLS)
Oct. 2012

CW and mode-locked operation of Yb3+-doped Lu3Al5O12 ceramic laser
H. Nakao, A; Shirakawa; K. Ueda; H. Yagi; T. Yanagitani
Oral presentation, English, International Workshop on Laser Science (IWLS)
Oct. 2012

Next-Generation Laser Sources from ILS/UEC
Akira Shirakawa
Oral presentation, English, International Workshop on Laser Science (IWLS)
Oct. 2012

Yb添加マルチコアフォトニック結晶ファイバーによるファイバー増幅
文全営; 白川晃
Oral presentation, Japanese, 第81回応用物理学会秋季学術講演会, 応用物理学会, オンライン, Domestic conference
08 Sep. 2012

High power fiber lasers by structured fibers
Akira Shirakawa
Invited oral presentation, English, 5th EPS-QED Europhoton Conference 2012, 5th EPS-QED Europhoton Conference 2012, Stockholm, Sweden, International conference
Aug. 2012

Mode-locked Yb3+-doped Lu3Al5O12 ceramic laser
H. Nakao; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani
Oral presentation, English, 5th EPS-QED Europhoton Conference 2012
Aug. 2012

Single frequency amplification by ytterbium doped photonic bandgap fiber at 1178 nm
M. Chen; X. Fan; A. Shirakawa; K. Ueda; C. B. Olausson; J. K. Lyngsø J. Broeng
Oral presentation, English, 5th EPS-QED Europhoton Conference 2012
Aug. 2012

Efficient CW laser operation of Yb:LuAG ceramic laser
H. Nakao; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani
Oral presentation, English, CLEO 2012
May 2012

53.6 W, 1178 nm Yb-doped photonic bandgap fiber oscillator
X. Fan; M. Chen; A. Shirakawa; K. Ueda; C. B. Olausson; J. Broeng
Oral presentation, English, CLEO 2012
May 2012

High power photonic bandgap fiber sources
A. Shirakawa; M. Chen; Y. Suzuki; X. Fan; K. Ueda; C. B. Olausson; J. K. Lyngsø J. Broeng
Invited oral presentation, English, The 8th Asia Pacific Laser Symposium (APLS 2012), The 8th Asia Pacific Laser Symposium (APLS 2012), Huangshan, China, International conference
May 2012

Single frequency amplification by ytterbium doped photonic bandgap fiber at 1178 nm
M. Chen; X. Fan; A. Shirakawa; K. Ueda; C. B. Olausson; J. K. Lyngsø J. Broeng
Oral presentation, English, The 8th Asia Pacific Laser Symposium (APLS 2012)
May 2012

High power solid-core photonic bandgap fiber laser at 1178 nm
X. Fan; M. Chen; A. Shirakawa; K. Ueda
Oral presentation, English, Workshop on Fiber Laser and Solid-state Laser at SIOM
Mar. 2012

受動モード同期Yb:LuAG セラミックレーザー
中尾博明; 白川晃; 植田憲一; 八木秀喜; 柳谷高公
Oral presentation, Japanese, 第12回レーザー学会東京支部研究会,第12回レーザー学会東京支部研究会
Mar. 2012

半導体レーザー励起Yb 添加LuAG セラミックレーザー
中尾博明; 白川晃; 植田憲一; 八木秀喜; 柳谷高公
Oral presentation, Japanese, 第59回応用物理学関係連合講演会,第59回応用物理学関係連合講演会
Mar. 2012

Photonic bandgap and multicore fiber lasers for next-generation lasers
A. Shirakawa; K. Ueda
Invited oral presentation, English, Workshop on Fiber Laser and Solid-state Laser at SIOM, SIOM, Shanghai, China, International conference
Mar. 2012

Phase-locked multi-core photonic crystal fiber laser by end-sealing
A. Shirakawa; H. Yamada; M. Matsumoto; M. Tokurakawa; K. Ueda
Oral presentation, English, Photonics West/LASE 2012
Jan. 2012

High-power single-frequency photonic bandgap fiber amplifier at 1178 nm
M. Chen; A. Shirakawa; Y. Yamahara; K. Ueda; C. B. Olausson; J. K. Lyngsø J. Broeng
Oral presentation, English, Photonics West/LASE 2012
Jan. 2012

Yb添加LuAGセラミックのレーザー及び分光特性
中尾博明; 白川晃; 植田憲一; 八木秀喜; 柳谷高公
Oral presentation, Japanese, レーザー学会学術講演会第32回年次大会,レーザー学会学術講演会第32回年次大会
Jan. 2012

LEDを用いたYb添加ファイバーのフォトブリーチング
深谷崇文; 白川晃; 植田憲一
Oral presentation, Japanese, レーザー学会学術講演会第32回年次大会,レーザー学会学術講演会第32回年次大会
Jan. 2012

Frontier of fiber lasers: photonic bandgap and multicore fiber lasers
Akira Shirakawa
Invited oral presentation, English, INDO–JAPAN International Workshop on Specialty Optical Fiber, Nano-Photonics and Devices, Kolkata, India, International conference
Jan. 2012

高出力ファイバーレーザー その歴史と潜在能力
植田憲一; 白川晃; 武者満
Invited oral presentation, Japanese, レーザー学会学術講演会第32回年次大会, レーザー学会
Jan. 2012

位相同期マルチコアフォトニック結晶ファイバーレーザーのQスイッチ動作
山田英典; 戸倉川正樹; 白川晃; 植田憲一
Oral presentation, Japanese, 第8回ナノ未来材料とコヒーレント光科学合同シンポジウム,第8回ナノ未来材料とコヒーレント光科学合同シンポジウム
Dec. 2011

LEDを用いたYb添加ファイバーのフォトブリーチング
深谷崇文; 白川晃; 植田憲一
Oral presentation, Japanese, 第8回ナノ未来材料とコヒーレント光科学合同シンポジウム,第8回ナノ未来材料とコヒーレント光科学合同シンポジウム
Dec. 2011

高出力単一周波数1178nmファイバー光源の開発
陳明晨; 山原佳晃; 白川晃; 植田憲一; C. B. Olausson; J. Broeng
Oral presentation, Japanese, 第4回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム,第4回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム
Nov. 2011

High Power Photonic Bandgap Fiber Sources
Akira Shirakawa
Invited oral presentation, English, Asia Communications and Photonics Conference (ACP) 2011, SPIE, Shanghai, China, International conference
Nov. 2011

Investigation of the laser and optical properties of new laser materials
H. Nakao; A. Shirakawa; K. Ueda; A. A. Kaminskii; S. Kuretake; N. Tanaka; Y. Kintaka; K. Kageyama; H. Yagi; T. Yanagitani
Invited oral presentation, English, 7th Laser Ceramics Symposium, 7th Laser Ceramics Symposium, Singapore,, International conference
Nov. 2011

Continuous wave and mode-locked laser based on Yb3+:Y2O3 ceramic thin disk
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; K. Beil; C. Krä nkel, K. Petermann; G. Huber
Invited oral presentation, English, 7th Laser Ceramics Symposium, 7th Laser Ceramics Symposium, Singapore, International conference
Nov. 2011

フォトニックバンドギャップおよびマルチコアによる新世代ファイバーレーザー
白川晃
Invited oral presentation, Japanese, 第4回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム, 第4回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム
Nov. 2011

高出力Yb3+:Y2O3 セラミック薄型ディスクレーザーの開発
戸倉川正樹; 白川晃; 植田憲一; 八木秀喜; 柳谷高公; K. Beil; C. Krä nkel,K. Petermann; G. Huber; A. A. Kaminskii
Oral presentation, Japanese, 第4回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム,第4回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム
Nov. 2011

High-order mode selection in Yb:YAG ceramic laser
M. P. Thirugnanasambandam; Y. Senatsky; A. Shirakawa; K. Ueda
Oral presentation, English, 第4回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム,第4回文部科学省「最先端の光の創成を目指したネットワーク研究拠点プログラム」シンポジウム
Nov. 2011

時代をつくる新しいレーザー
白川晃
Invited oral presentation, Japanese, JPCフォーラム, JPCフォーラム
Sep. 2011

マルチコアアンプ用光ファイバ技術
姚兵; 大薗和正; 関谷晴彦エジソン; 齋藤和也; 白川晃
Invited oral presentation, Japanese, 通信インフラの飛躍的な高度化に関する時限研究専門委員会（EXAT）研究会, 電子情報通信学会
Aug. 2011

Q-switched multicore photonic crystal fiber laser phase-locked by end-seal technique
A. Shirakawa; M. Matsumoto; T. Kobayashi; M. Tokurakawa; K. Ueda
Oral presentation, English, CLEO-Pacific Rim 2011
Aug. 2011

LED側面照射によるYb添加ファイバーのフォトブリーチング
深谷崇文; 白川晃; 植田憲一
Oral presentation, Japanese, 第72回応用物理学会学術講演会,第72回応用物理学会学術講演会
Aug. 2011

Qスイッチ位相同期マルチコアフォトニック結晶ファイバーレーザー
山田英典; 松本道生; 戸倉川正樹; 白川晃; 植田憲一
Oral presentation, Japanese, 第72回応用物理学会学術講演会,第72回応用物理学会学術講演会
Aug. 2011

単一周波数1178nmYb添加フォトニックバンドギャップファイバー増幅器
陳明晨; 山原佳晃; 白川晃; 植田憲一; C. B. Olausson; J. Broeng
Oral presentation, Japanese, 第72回応用物理学会学術講演会,第72回応用物理学会学術講演会
Aug. 2011

相転移によるNa,Nd共添加Ca2MgSi2O7レーザーの特性変化
中尾博明; 白川晃; 植田憲一; L. Bohaty; P. Becker; A. Kaminskii
Oral presentation, Japanese, 第72回応用物理学会学術講演会,第72回応用物理学会学術講演会
Aug. 2011

高出力Yb3+:Y2O3 セラミック薄型ディスクレーザーの開発
戸倉川正樹; 白川晃; 植田憲一; 八木秀喜; 柳谷高公; K. Beil; C. Krankel; K. Petermann; G. Huber
Oral presentation, Japanese, 第72回応用物理学会学術講演会,第72回応用物理学会学術講演会
Aug. 2011

High Power Photonic Bandgap Fiber Lasers
A. Shirakawa; M. Chen; X. Fan; K. Ueda; C. B. Olausson; J. K. Lyngsø J. Broeng
Invited oral presentation, English, 16th Opto-Electronics and Communications Conference (OECC) 2011, 16th Opto-Electronics and Communications Conference (OECC) 2011, Kaohsiung, Taiwan, International conference
Jul. 2011

All-solid Photonic Bandgap Fiber Lasers
C. B. Olausson; A. Shirakawa; J. K. Lyngsø K. P. Hansen; J. Broeng; K. Ueda
Invited oral presentation, English, Specialty Optical Fibers, Specialty Optical Fibers, Toronto, Canada, International conference
Jun. 2011

Single-frequency photonic bandgap fiber amplification
A. Shirakawa; M. Chen; Y. Yamahara; K. Ueda; C. B. Olausson; K. Lyngsø J. Broeng
Oral presentation, English, CLEO 2011
May 2011

Na,Nd co-doped Ca2MgSi2O7 laser
H. Nakao; A. Shirakawa; K. Ueda; L. Bohaty; P. Becker; A. A. Kaminski
Oral presentation, English, CLEO/Europe 2011
May 2011

ASSP 2011 報告
白川晃
Others, Japanese, (財)光産業技術振興協会2010年度第４回光材料・応用技術研究会, Invited, Domestic conference
04 Mar. 2011

Frontier and future of high power fiber lasers
A. Shirakawa; K. Ueda
Invited oral presentation, English, JSPS Asian CORE Workshop on Next Generation Ultra-Short Pulse Lasers for High Field and Ultrafast Science, JSPS Asian CORE Workshop on Next Generation Ultra-Short Pulse Lasers for High Field and Ultrafast Science, Wako, Japan, International conference
Mar. 2011

Yb添加フォトニックバンドギャップファイバーによる単一周波数光増幅
陳明晨; 山原佳晃; 白川晃; 植田憲一; C. Olausson; J. Broeng
Oral presentation, Japanese, 第58回応用物理学関係連合講演会,第58回応用物理学関係連合講演会
Mar. 2011

LEDを用いたYb添加ファイバーのフォトブリーチング
深谷崇文; 井上雅行; 白川晃; 植田憲一
Oral presentation, Japanese, 第58回応用物理学関係連合講演会,第58回応用物理学関係連合講演会
Mar. 2011

Na,Nd共添加Ca2MgSi2O7レーザーにおける相転移による特異な振る舞い
中尾博明; 白川晃; 植田憲一; L. Bohaty; P. Becker; A. Kaminskii
Oral presentation, Japanese, 第58回応用物理学関係連合講演会,第58回応用物理学関係連合講演会
Mar. 2011

All-fiber phase-locked multi-core photonic crystal fiber laser
M. Matsumoto; T. Kobayashi; A. Shirakawa; K. Ueda
Oral presentation, English, Advanced Solid-State Photonics 2011
Feb. 2011

High power ytterbium fiber lasers at extremely long wavelengths by photonic bandgap fiber technology
A. Shirakawa; M. Chen; K. Ueda; C. B. Olausson; J. K. Lyngsø J. Broeng
Invited oral presentation, English, IEEE Winter Topical Meeting (WTM) 2011, IEEE Winter Topical Meeting (WTM) 2011, Keystone, Colorado, USA, International conference
Jan. 2011

ファイバーレーザーの高出力化のための位相同期マルチコアファイバーレーザー
松本道生; 白川晃; 植田憲一
Invited oral presentation, Japanese, レーザー学会学術講演会第31回年次大会, レーザー学会
Jan. 2011

NdドープBa(Mg,Zr,Ta)O3セラミックレーザーの研究
呉竹悟志; 田中伸彦; 金高祐二; 景山恵介; 黒川裕章; 戸倉川正樹; 白川晃; 植田憲一; A. Kaminskii
Oral presentation, Japanese, レーザー学会学術講演会第31回年次大会,第31回レーザー学会年次大会
Jan. 2011

Nd3+-doped Ba(Zr4+,Mg2+,Ta5+)O3 ceramics as laser materials
S. Kuretake; N. Tanaka; Y. Kintaka; K. Kageyama; H. Takagi; H. Nakao; M. Tokurakawa; A. Shirakawa; K. Ueda; A. A. Kaminskii
Invited oral presentation, English, 6th Laser Ceramics Symposium, 6th Laser Ceramics Symposium, Münster, Germany, International conference
Dec. 2010

新世代コヒーレント光源を目指した電通大レーザー研におけるレーザー研究
白川晃
Invited oral presentation, English, エクストリームフォトニクスセミナー, 理化学研究所
Oct. 2010

エンドシールによる全ファイバー高効率位相同期マルチコアフォトニック結晶ファイバーレーザーIII
松本道生; 小林哲也; 白川晃; 植田憲一
Oral presentation, Japanese, 第71回応用物理学会学術講演会,第71回応用物理学会学術講演会
Sep. 2010

1178nm 単一周波数ファイバー光源の開発」，第71回応用物理学会学術講演会
陳明晨; C. B. Olausson; 白川晃; 植田憲一
Oral presentation, Japanese, 第71回応用物理学会学術講演会,第71回応用物理学会学術講演会
Sep. 2010

Na,Nd 共添加Ca2MgSi2O7 レーザー」，第71回応用物理学会学術講演会
中尾博明; 白川晃; 植田憲一; L. Bohaty; P. Becker; A. A. Kaminskii
Oral presentation, Japanese, 第71回応用物理学会学術講演会,第71回応用物理学会学術講演会
Sep. 2010

Yb3+添加薄型ディスク媒質を用いたカーレンズモード同期レーザーの開発
戸倉川正樹; 白川晃; 植田憲一
Oral presentation, Japanese, 第71回応用物理学会学術講演会,第71回応用物理学会学術講演会
Sep. 2010

New generation fiber lasers by photonic bandgap and multicore fibers
Akira Shirakawa
Invited oral presentation, English, PMRC Colloquium, PMRC Colloquium at Japan Atomic Energy Agency, Kizugawa, Japan, International conference
Sep. 2010

ファイバレーザの高出力化
姚兵; 大薗和正; 本郷晃史; 白川晃
Invited oral presentation, Japanese, 2010ソサイエティー大会, 電子情報通信学会
Sep. 2010

新しいファイバーレーザー：フォトニックバンドギャップファイバーレーザー
白川晃
Invited oral presentation, Japanese, 学振130委員会平成22年度第1回研究会, 学振130委員会平成22年度第1回研究会
May 2010

Diode-pumped mode-locked Nd3+-doped Ba(Zr,Mg,Ta)O3 ceramic laser
H. Kurokawa; M. Tokurakawa; A. Shirakawa; K. Ueda; A. A. Kaminskii; S. Kuretake; N. Tanaka; Y. Kintaka; K. Kageyama
Oral presentation, English, CLEO/QELS 2010
May 2010

Photodarkening and photobleaching of Yb-doped fibers by laser diodes
N. Inoue; A. Shirakawa; K. Ueda
Oral presentation, English, CLEO/QELS 2010
May 2010

167 W, 1178 nm Ytterbium-doped photonic bandgap fiber amplifier with power scalability
C. B. Olausson; A. Shirakawa; M. Chen; J. K. Lyngsø J. Broeng; K. P. Hansen; A. Bjarklev; K. Ueda
Oral presentation, English, CLEO/QELS 2010
May 2010

All-fiber phase-locked multi-core photonic crystal fiber laser with fill-factor enhancement and high efficiency
A. Shirakawa; T. Kobayashi; M. Matsumoto; K. Ueda
Oral presentation, English, CLEO/QELS 2010
May 2010

167 W ASE-free and power scalable Yb-doped photonic bandgap fiber amplifier at 1178 nm
K. Ueda; A. Shirakawa; C. B. Olausson
Invited oral presentation, English, 7th Asia-Pacific Laser Symposium, 7th Asia-Pacific Laser Symposium, Cheju, Korea, International conference
May 2010

High-power photonic bandgap fiber sources
Akira Shirakawa
Invited oral presentation, English, US Air Force/AOARD Window-On-Science Seminar, US Air Force/AOARD Window-On-Science Seminar, Albuquerque, USA, International conference
Mar. 2010

高出力フォトニックバンドギャップファイバー光源
白川晃
Invited oral presentation, Japanese, 第10回レーザー学会東京支部研究会/電気学会光量子デバイス技術研究会, 第10回レーザー学会東京支部研究会/電気学会光量子デバイス技術研究会
Mar. 2010

167W, 1178nmYb添加フォトニックバンドギャップファイバー増幅器
白川晃; 陳明晨; 植田憲一; C. B. Olausson; J. K. Lyngsø J. Broeng
Oral presentation, Japanese, 第57回応用物理学関係連合講演会,第57回応用物理学関係連合講演会
Mar. 2010

エンドシールによる全ファイバー高効率位相同期マルチコアフォトニック結晶ファイバーレーザーＩ
小林哲也; 松本道生; 白川晃; 植田憲一
Oral presentation, Japanese, 第57回応用物理学関係連合講演会,第57回応用物理学関係連合講演会
Mar. 2010

エンドシールによる全ファイバー高効率位相同期マルチコアフォトニック結晶ファイバーレーザーII
松本道生; 小林哲也; 白川晃; 植田憲一
Oral presentation, Japanese, 第57回応用物理学関係連合講演会,第57回応用物理学関係連合講演会
Mar. 2010

利得帯媒質の飽和効果競合に基づくパルス幅制限の計算
戸倉川正樹; 白川晃; 植田憲一
Oral presentation, Japanese, 第57回応用物理学関係連合講演会,第57回応用物理学関係連合講演会
Mar. 2010

Nd3+:Ba(Zr,Mg,Ta)O3セラミックモード同期レーザー
黒川裕章; 戸倉川正樹; 白川晃; 植田憲一; A. Kaminskii; 呉竹悟志; 田中伸彦; 金高祐二; 景山恵介
Oral presentation, Japanese, 第57回応用物理学関係連合講演会,第57回応用物理学関係連合講演会
Mar. 2010

サブ70fsカーレンズモード同期Yb3+:(YGd2)Sc2(GaAl2)O12セラッミクレーザー
戸倉川正樹; 黒川裕章; 白川晃; 植田憲一; 八木秀喜; 柳谷高公; A. Kaminskii
Oral presentation, Japanese, 第57回応用物理学関係連合講演会,第57回応用物理学関係連合講演会
Mar. 2010

Estimation of gain bandwidth limitation of short pulse duration based on competition of gain saturation
M. Tokurakawa; A. Shirakawa; K. Ueda
Oral presentation, English, Advanced Solid-State Photonics 2010
Feb. 2010

Power-scalable photonic bandgap fiber sources with 167 W, 1178 nm and 14.5 W, 589 nm radiations
A. Shirakawa; C. B. Olausson; M. Chen; K. Ueda; J. K. Lyngsø J. Broeng
Oral presentation, English, Advanced Solid-State Photonics 2010
Feb. 2010

Power-scalable long-wavelength Yb-doped photonic bandgap fiber sources
A. Shirakawa; H. Maruyama; K. Ueda; C. B. Olausson; J. K. Lyngsø J. Broeng
Oral presentation, English, Photonics West/LASE 2010
Jan. 2010

Broadband-gain Nd3+-doped Ba(Zr,Mg,Ta)O3 ceramic lasers for ultrashort pulse generation
A. Shirakawa; H. Kurokawa; M. Tokurakawa; K. Ueda; N. Tanaka; Y. Kintaka; S. Kuretake; K. Kageyama; H. Takagi; A. A. Kaminskii
Invited oral presentation, English, 5th Laser Ceramics Symposium, 5th Laser Ceramics Symposium, Bilbao, Spain, International conference
Dec. 2009

Ultrashort pulses from diode-pumped Yb3+-doped ceramic lasers
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. A. Kaminskii
Invited oral presentation, English, 5th Laser Ceramics Symposium, 5th Laser Ceramics Symposium, Bilbao, Spain, International conference
Dec. 2009

マルチコアフォトニック結晶ファイバーレーザーのin-phaseモード選択励振
松本道生; 小林哲也; 白川晃; 植田憲一
Oral presentation, Japanese, 第６回ナノ未来材料とコヒーレント光科学合同シンポジウム,第６回ナノ未来材料とコヒーレント光科学合同シンポジウム
Dec. 2009

Generation of beams with near-diffraction free propagation characteristics in Yb:YAG laser using an intracavity lens with spherical aberration
M. P. Thirugnanasambandam; Y. Senatsky; A. Shirakawa; K. Ueda
Oral presentation, English, The 5th Asian Symposium on Intense Laser Science (ASILS-5)
Dec. 2009

Fiber laser research in ILS/UEC ~ focusing on power limit, coherent beam combing, and related topics
Akira Shirakawa
Invited oral presentation, English, Asian-Core Ultrafast Pulse Seminar at Institute of Physics, Asian-Core Ultrafast Pulse Seminar at Institute of Physics, Beijing, China, International conference
Nov. 2009

LD直接励起フェムト秒Yb添加セラミックレーザ
戸倉川正樹; 白川晃; 植田憲一
Invited oral presentation, Japanese, 第3回超高速光エレクトロニクス研究会, 第3回超高速光エレクトロニクス研究会
Nov. 2009

黒川裕章，戸倉川正樹，白川晃，植田憲一，A. Kaminskii，田中伸彦，金高祐二，呉竹悟志，景山恵介
黒川裕章; 戸倉川正樹; 白川晃; 植田憲一; A. Kaminskii; 田中伸彦; 金高祐二; 呉竹悟志; 景山恵介
Oral presentation, Japanese, 日本光学会年次学術講演会Optics & Photonics Japan 2009,日本光学会年次学術講演会Optics & Photonics Japan 2009
Nov. 2009

高出力1178nmYb添加フォトニックバンドギャップファイバー増幅と589nmSHG
白川晃; 丸山裕輝; 植田憲一; C. B. Olausson; J. K. Lyngsø J. Broeng
Oral presentation, Japanese, 第70回応用物理学会学術講演会,第70回応用物理学会学術講演会
Sep. 2009

マルチコアフォトニック結晶ファイバーレーザーのin-phaseモード選択励振
小林哲也; 松本道生; 白川晃; 植田憲一
Oral presentation, Japanese, 第70回応用物理学会学術講演会,第70回応用物理学会学術講演会
Sep. 2009

近紫外LDを用いたphotodarkeningフリーなYb添加ファイバーレーザーの研究
井上雅行; 丸山裕輝; 白川晃; 植田憲一
Oral presentation, Japanese, 第70回応用物理学会学術講演会,第70回応用物理学会学術講演会
Sep. 2009

カーレンズモード同期Yb添加三二酸化物レーザー
戸倉川正樹; 黒川裕章; 白川晃; 植田憲一; R. Peters; S. T. Fredrich-Thornton; K. Petermann; G. Huber
Oral presentation, Japanese, 第70回応用物理学会学術講演会,第70回応用物理学会学術講演会
Sep. 2009

Rare-earth doped transparent Ba(Zr,Mg,Ta)O3 ceramics for lasers
N. Tanaka; S. Kuretake; Y. Kintaka; K. Kageyama; H. Takagi; K. Ueda; A. Shirakawa; M. Tokurakawa; H. Kurokawa; A. A. Kaminskii
Invited oral presentation, English, 6th China International Conference on High-Performance Ceramics, 6th China International Conference on High-Performance Ceramics, Harbin, China, International conference
Aug. 2009

Femtosecond diode-pumped Yb-doped crystal and ceramic lasers with high average power
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. A. Kaminskii; R. Peters; S. T. Fredrich-Thornton; K. Petermann; G. Huber
Invited oral presentation, English, 18th International Laser Physics Workshop, 18th International Laser Physics Workshop, Barcelona, Spain, International conference
Jul. 2009

30W, 1178nm Yb-doped photonic bandgap fiber amplifier
A. Shirakawa; H. Maruyama; K. Ueda; C. B. Olausson; J. K. Lyngsø J. Broeng
Invited oral presentation, English, CLEO/QELS 2009, CLEO/QELS 2009, Baltimore, USA, International conference
Jun. 2009

Continuous-wave and mode-locked laser operations based on Yb3+:(YGd2)Sc2(GaAl2)O12 disordered ceramic
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. A. Kaminskii
Oral presentation, English, CLEO/QELS 2009
Jun. 2009

High-power scaling of Yb fiber laser in the long wavelength range
Akira Shirakawa
Others, English, Special Seminar, Laser Zentrum Hannover
Jun. 2009

High-power scaling of Yb fiber laser in the long wavelength range
Akira Shirakawa
Others, English, Special Seminar, Laser Zentrum Hannover
Jun. 2009

1178 nm Yb-doped Solid-core Photonic Bandgap Fiber Laser Source for 589nm Generation
H. Maruyama; A. Shirakawa; K. Ueda; C. B. Olausson; J. K. Lyngsø J. Broeng
Oral presentation, English, CLEO Europe/EQEC 2009
Jun. 2009

Crystalline-orientation Selected Linearly Polarized Yb:YAG Microchip Laser
J. Dong; A. Shirakawa; K. Ueda
Oral presentation, English, CLEO Europe/EQEC 2009
Jun. 2009

Passively Q-switched Nd:YAG microchip laser emits radially and azimuthally polarized light
J. Li; K. Ueda; A. Shirakawa; L. Zhong
Oral presentation, English, CLEO Europe/EQEC 2009
Jun. 2009

Generation of near diffraction free beams in Yb:YAG laser using an intracavity lens with spherical aberration
Yu. Senatsky; A. Shirakawa; K. Ueda
Oral presentation, English, CLEO Europe/EQEC 2009
Jun. 2009

単一周波数1178nm外部共振器半導体レーザーの製作とそのファイバーラマン増幅
小宮山恭平; 白川晃; 植田憲一
Oral presentation, Japanese, 第9回レーザー学会東京支部研究会,第9回レーザー学会東京支部研究会
Mar. 2009

Yb3+:(YGd2)Sc2(GaAl2)O12セラミックレーザー
戸倉川正樹; 黒川裕章; 白川晃; 植田憲一; 八木秀喜; 柳谷高公; A. A. Kaminskii
Oral presentation, Japanese, 第56回応用物理学関係連合講演会,第56回応用物理学関係連合講演会
Mar. 2009

High-power scaling of Yb fiber laser in the long wavelength range
Akira Shirakawa
Others, English, Special Lecture, Xiamen University
Mar. 2009

Ultra-Short Pulses from Diode‐Pumped Yb3+-Doped Crystal and Ceramic Lasers with High Average Power
M. Tokurakawa; A. Shirakawa; K. Ueda; R. Peters; S. T. Fredrich-Thornton; K. Petermann; G. Huber; H. Yagi; T. Yanagitani; A. A. Kaminskii
Oral presentation, English, Advanced Solid-State Photonics 2009
Feb. 2009

広帯域利得Nd添加Ba(Mg,Zr,Ta)O3セラミックレーザー
黒川裕章; 戸倉川正樹; 白川晃; 植田憲一; A. Kaminskii; 田中伸彦; 金高祐二; 呉竹悟志; 景山恵介; 鷹木洋
Oral presentation, Japanese, 第29回レーザー学会年次大会,第29回レーザー学会年次大会
Jan. 2009

Talbot共振器によるマルチコアファイバーレーザーのin-phaseモード選択励振
小林哲也; 白川晃; 植田憲一
Oral presentation, Japanese, 第29回レーザー学会年次大会,第29回レーザー学会年次大会
Jan. 2009

Yb添加フォトニックバンドギャップファイバーによる1150-1200nm光増幅器
丸山裕輝; 白川晃; 植田憲一; C. B. Olausson; J. K. Lyngsø B. Mangan; J. Broeng
Oral presentation, Japanese, 第29回レーザー学会年次大会,第29回レーザー学会年次大会
Jan. 2009

High-power Yb-doped solid-core photonic bandgap fiber amplifier at 1150-1200nm
A. Shirakawa; H. Maruyama; K. Ueda; C. B. Olausson; J. K. Lyngsø B. Mangan; J. Broeng
Oral presentation, English, Photonics West/LASE 2009
Jan. 2009

Yb添加超短パルス固体レーザー
戸倉川正樹; 黒川裕章; 白川晃; 植田憲一; 八木秀喜; 柳谷高公; A. A. Kaminskii
Oral presentation, Japanese, 第５回ナノ未来材料とコヒーレント光科学合同シンポジウム,第５回ナノ未来材料とコヒーレント光科学合同シンポジウム
Dec. 2008

Yb添加フォトニックバンドギャップファイバーによる1150-1200nm光増幅器
丸山裕輝; 白川晃; 植田憲一; C. B. Olausson; J. K. Lyngsø B. Mangan; J. Broeng
Oral presentation, Japanese, 第５回ナノ未来材料とコヒーレント光科学合同シンポジウム,第５回ナノ未来材料とコヒーレント光科学合同シンポジウム
Dec. 2008

Rare-earth doped disordered transparent Ba(Zr,Mg,Ta)O3 ceramics
N. Tanaka; S. Kuretake; Y. Kintaka; K. Kageyama; H. Takagi; K. Ueda; A. Shirakawa; M. Tokurakawa; H. Kurokawa; A. A. Kaminskii
Invited oral presentation, English, 4th Laser Ceramics Symposium, 4th Laser Ceramics Symposium, Shanghai, International conference
Nov. 2008

High-Power Yb-Doped Solid-Core Photonic Bandgap Fiber Amplifier at 1150-1200nm
H. Maruyama; A. Shirakawa; K. Ueda; C. B. Olausson; J. K. Lyngsø B. Mangan; J. Broeng
Oral presentation, English, Frontiers in Optics/Laser Science XXIV Conference 2008
Oct. 2008

High-power scaling of Yb fiber laser in the long wavelength range
A. Shirakawa; H. Maruyama; K. Ueda
Invited oral presentation, English, IEEJ International Workshop on Quantum and Optical Devices, IEEJ International Workshop on Quantum and Optical Devices, Hilo, USA, International conference
Sep. 2008

カーレンズモード同期Yb添加複合利得媒質セラミックレーザー
戸倉川正樹; 黒川裕章; 白川晃; 植田憲一; 八木秀喜; 柳谷高公; A. A. Kaminskii
Invited oral presentation, Japanese, 第69回応用物理学会学術講演会, 第69回応用物理学会学術講演会
Sep. 2008

MgOセラミックスの熱誘起複屈折
黒川裕章; 戸倉川正樹; 白川晃; 植田憲一; 鎌倉高広; 八木秀喜; 柳谷高公
Oral presentation, Japanese, 第69回応用物理学会学術講演会,第69回応用物理学会学術講演会
Sep. 2008

Yb添加フォトニックバンドギャップファイバーによる1150-1200nm光増幅器
丸山裕輝; 白川晃; 植田憲一; C. B. Olausson; J. K. Lyngsø B. Mangan; J. Broeng
Oral presentation, Japanese, 第69回応用物理学会学術講演会,第69回応用物理学会学術講演会
Sep. 2008

Yb添加ファイバーのphotodarkeningに対するphotobleachingの研究
井上雅行; 丸山裕輝; 白川晃; 植田憲一
Oral presentation, Japanese, 第69回応用物理学会学術講演会,第69回応用物理学会学術講演会
Sep. 2008

カーレンズモード同期Yb添加複合利得媒質セラミックレーザー
戸倉川正樹; 黒川裕章; 白川晃; 植田憲一; 八木秀喜; 柳谷高公; A. A. Kaminskii
Invited oral presentation, Japanese, 第69回応用物理学会学術講演会, 第69回応用物理学会学術講演会
Sep. 2008

Circular modes selection in Yb:YAG laser using an intracavity lens with spherical aberration
J.-F. Bisson; A.Shirakawa; K. Ueda; Yu. Senatsky
Oral presentation, English, Laser Optics 2008
Jun. 2008

Diode-pumped sub 60-fs Kerr-lens mode-locked Yb-doped sesquioxide combined ceramic laser
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. Kaminskii
Oral presentation, English, CLEO/QELS 2008
May 2008

High-brightness 210 uJ pulsed Raman fiber source
A. Shirakawa; C. A. Codemard; J. Ji; K. K. Cheng; A. Malinowski; D. J. Richardson; J .K. Sahu; J. Nilsson
Oral presentation, English, CLEO/QELS 2008
May 2008

次世代高出力フェムト秒セラミックレーザーの挑戦と展望
白川晃
Invited oral presentation, Japanese, 第63回年次大会 ビーム物理領域合同シンポジウム, 日本物理学会
Mar. 2008

Yb添加マルチコアファイバーレーザーのin-phaseモード選択励振
小林哲也; 白川晃; 植田憲一
Oral presentation, Japanese, 第8回レーザー学会東京支部研究会,第８回レーザー学会東京支部研究会
Mar. 2008

Yb添加ファイバーのPhotodarkeningに対するPhotobleachingの研究
井上雅行; 丸山裕輝; 白川晃; 植田憲一
Oral presentation, Japanese, 第8回レーザー学会東京支部研究会,第8回レーザー学会東京支部研究会
Mar. 2008

MgOセラミックスの熱誘起複屈折
黒川裕章; 戸倉川正樹; 白川晃; 植田憲一; 鎌倉高広; 八木秀喜; 柳谷高公
Oral presentation, Japanese, 第8回レーザー学会東京支部研究会,第8回レーザー学会東京支部研究会
Mar. 2008

カーレンズモード同期Yb添加複合利得媒質セラミックレーザー
戸倉川正樹; 白川晃; 植田憲一; 八木秀喜; 柳谷高公; A. A. Kaminskii
Oral presentation, Japanese, 第55回応用物理学関係連合講演会,第55回応用物理学関係連合講演会
Mar. 2008

Yb添加フォトニックバンドギャップファイバーによる1178nm増幅
丸山裕輝; 白川晃; 植田憲一
Oral presentation, Japanese, 第55回応用物理学関係連合講演会,第55回応用物理学関係連合講演会
Mar. 2008

Yb添加マルチコアファイバーレーザーのin-phaseモード選択励振
小林哲也; 白川晃; 植田憲一
Oral presentation, Japanese, 第8回レーザー学会東京支部研究会,第８回レーザー学会東京支部研究会
Mar. 2008

Yb-ASE-Free Er Amplification in Short-Wavelength Filtered Er:Yb Photonic-Crystal Fiber
Akira Shirakawa; Hiroyuki Suzuki; Motoyuki Tanisho; Ken-ichi Ueda
Oral presentation, English, Optical Fiber Communication Conference 2008, Anaheim
Feb. 2008

カーレンズモード同期Yb3+:Lu2O3:Y2O3複合セラミックレーザー
戸倉川正樹; 白川晃; 植田憲一; 八木秀喜; 柳谷高公; A. A. Kaminskii
Oral presentation, Japanese, 第28回レーザー学会年次大会,第28回レーザー学会年次大会
Feb. 2008

Diode-pumped Kerr-lens mode-locked Yb-doped sesquioxide ceramic laser
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. Kaminskii
Oral presentation, English, APLS 2008, Nagoya
Jan. 2008

Diode-pumped Kerr-lens mode-locked Yb3+:Sc2O3 and Yb3+:Y2O3 combined active media ceramic laser
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. Kaminskii
Oral presentation, English, Advanced Solid-State Photonics 2008, Nara
Jan. 2008

Diode-pumped 65-fs Kerr-lens mode-locked combined Yb-doped sesquioxide ceramic laser
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. Kaminskii
Oral presentation, English, Advanced Solid-State Photonics 2008, Nara
Jan. 2008

Diode-pumped sub 100-fs Kerr-lens mode-locking Yb3+:Sc2O3 ceramic laser with high average power
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. Kaminskii
Oral presentation, English, Advanced Solid-State Photonics 2008, Nara
Jan. 2008

1178nm linearly-polarized all fiber laser
丸山裕輝; 白川晃; 植田憲一
Oral presentation, Japanese, 21世紀COE第4回合同シンポジウム,21世紀COE第4回合同シンポジウム
Dec. 2007

Diode-pumped Kerr-lens mode-locked sesquioxide ceramic lasers
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. A. Kaminskii
Invited oral presentation, English, COE International Symposium, COE International Symposium, Chofu, Japan, International conference
Dec. 2007

Efficient composite self-Q-switched microchip lasers
Jung Dong; Manasadevi Priamvadha; A. Shirakawa; K. Ueda
Oral presentation, English, COE International Symposium
Dec. 2007

1178nm linearly polarized all fiber laser
H. Maruyama; A. Shirakawa; K. Ueda
Oral presentation, English, COE International Symposium
Dec. 2007

Efficient ytterbium concentration on Yb:YAG microchip laser performance at ambient temperature
Jung Dong; S. Fredrich; Manasadevi Priamvadha; A. Shirakawa; K. Ueda
Oral presentation, English, COE International Symposium
Dec. 2007

Diode-pumped Kerr-lens mode-locked Yb3+:Sc2O3 ceramic laser
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. A. Kaminskii
Oral presentation, English, 3rd Laser Ceramic Symposium, Paris
Oct. 2007

波長可変Yb3+:Y2O3セラミックレーザー
戸倉川正樹; 白川晃; 植田憲一; 八木秀喜; 柳谷高公; A. A. Kaminskii
Oral presentation, Japanese, 応用物理学会,第68回応用物理学会学術講演会
Sep. 2007

1178nm linearly-polarized all fiber laser
H. Maruyama; A. Shirakawa; K. Ueda
Oral presentation, English, CLEO/Pacific Rim 2007, Seoul
Aug. 2007

CLEO/QELS 2007会議報告
白川晃
Others, Japanese, 電気学会次世代光・量子制御技術調査専門委員会, Invited, Domestic conference
08 Jun. 2007

Passively Q-switched Yb:YAG/Cr:YAG ceramics miniature lasers with peak power >150 kW and nearly diffraction-limited beam quality
J. Dong; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani
Oral presentation, English, CLEO/Europe 2007, Munich
Jun. 2007

Composite Yb:YAG/Cr:YAG ceramics self-Q-switched laser
J. Dong; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A. A. Kaminskii
Oral presentation, English, CLEO/QELS 2007, Baltimore
May 2007

Linearly-polarized Yb-doped Fiber Laser in an All-fiber Configuration
Akira Shirakawa; Makoto Kamijo; Jun Ota; Ken-ichi Ueda; Kiminori Mizuuchi; Hiroyuki Furuya; Kazuhisa Yamamoto
Oral presentation, English, CLEO/QELS 2007, Baltimore
May 2007

Single-Shot Fiber Dispersionmetry
Akira Shirakawa; Takayuki Atsumi; Motoyuki Tanisho; Ken-ichi Ueda
Oral presentation, English, Optical Fiber Communication Conference 2007, Anaheim
Mar. 2007

1178nm単一偏光ファイバーレーザーの高出力化
丸山裕輝; 白川晃; 植田憲一
Oral presentation, Japanese, レーザー学会,レーザー学会学術講演会第27回年次大会
Jan. 2007

複屈折中空フォトニックバンドギャップファイバーを用いた偏波保持ファイバーパルス圧縮
谷所基行; 鈴木博之; 白川晃; 植田憲一
Oral presentation, Japanese, レーザー学会,レーザー学会学術講演会第27回年次大
Jan. 2007

シングルモードYb系ファイバーレーザーの高出力化の現状と動向
白川晃; 植田憲一
Invited oral presentation, Japanese, レーザー学会学術講演会第27回年次大会, レーザー学会
Jan. 2007

Ambient-temperature 4-W Yb:YAG ceramic microchip lasers at both 1030 nm and 1049 nm
J. Dong; A. Shirakawa; K. Ueda; H. Yagi; T. Yanagitani; A.A. Kaminskii
Oral presentation, English, Advanced Solid-State Photonics 2007, Vancouver
Jan. 2007

Linearly-polarized Yb-doped fiber laser directly operating at 1178 nm for 589-nm generation
Akira Shirakawa; Jun Ota; Horoki Maruyama; Ken-ichi Ueda
Oral presentation, English, Advanced Solid-State Photonics 2007, Vancouver
Jan. 2007

Polarization-maintaining fiber pulse compressor by birefringent hollow-core photonic bandgap fiber
Akira Shirakawa; Motoyuki Tanisho; Ken-ichi Ueda
Oral presentation, English, Advanced Solid-State Photonics 2007, Vancouver
Jan. 2007

高出力全ファイバーチャープパルス増幅の研究
谷所基行; 鈴木博之; 白川晃; 植田憲一
Oral presentation, Japanese, 21世紀COE第3回合同シンポジウム,21世紀COE第3回合同シンポジウム
Dec. 2006

Mode-locking performance of Yb-doped sesquioxide nanocrystalline ceramic lasers
A. Shirakawa; M. Tokurakawa; K. Takaichi; K. Ueda; H. Yagi; S. Hosokawa; T. Yanagitani; A. A. Kaminskii
Invited oral presentation, English, 2nd Laser Ceramic Symposium, 2nd Laser Ceramic Symposium, Tokyo, Japan, International conference
Nov. 2006

Mode-locking performance of Yb-doped sesquioxide nanocrystalline ceramic lasers
A. Shirakawa; M. Tokurakawa; K. Takaichi; K. Ueda; H. Yagi; S. Hosokawa; T. Yanagitani; A. A. Kaminskii
Invited oral presentation, English, 2nd Laser Ceramic Symposium, 2nd Laser Ceramic Symposium, Tokyo, Japan, International conference
Nov. 2006

Diode-pumped mode-locked Yb-doped sesquioxide nanocrystalline ceramic lasers
M. Tokurakawa; A. Shirakawa; K. Ueda; H. Yagi; S. Hosokawa; T. Yanagitani; A. A. Kaminskii
Oral presentation, English, OSA Annual Meeting-Frontier in Optics 2006, Rochester
Oct. 2006

単一偏光1178nmYbファイバーレーザー
白川晃; 太田淳; 植田憲一
Oral presentation, Japanese, 応用物理学会,第67回応用物理学会学術講演会
Aug. 2006

複屈折率中空フォトニックバンドギャップファイバーによる偏波保持ファイバーパルス圧縮器
白川晃; 谷所基行; 植田憲一
Oral presentation, Japanese, 応用物理学会,第67回応用物理学会学術講演会
Aug. 2006

Fiber Laser Research in ILS/UEC
A. Shirakawa; K. Ueda
Invited oral presentation, English, Laser Optics 2006, Laser Optics 2006, St. Petersburg, St. Petersburg, Russia, International conference
Jun. 2006

Dispersion-managed All-fiber Chirped-pulse Amplifier yielding High-power Clean Sub-500-fs Pulses at 1.5 um
Akira Shirakawa; Motoyuki Tanisho; Ken-ichi Ueda
Oral presentation, English, CLEO/QELS 2006, Long Beach
May 2006

コヒーレントビーム結合によるファイバーレーザーのパワースケーリング：現状と課題
白川晃; 植田憲一
Invited oral presentation, Japanese, レーザー学会学術講演会第26回年次大会, レーザー学会
Feb. 2006

1178nmYb添加ダブルクラッドファイバーレーザーの研究
太田淳; 白川晃; 植田憲一
Oral presentation, Japanese, レーザー学会,レーザー学会学術講演会第26回年次大会
Feb. 2006

Single-frequency 1083 nm Ytterbium Doped Master Oscillator Power Amplifier Fiber Laser
Shenghong Huang; Akira Shirakawa; Mitsuru Musha; Ken-ichi Ueda
Oral presentation, English, レーザー学会,レーザー学会学術講演会第26回年次大会
Feb. 2006

大モード面積Er:Ybフォトニック結晶ファイバーを用いたフェムト秒全ファイバーチャープパルス増幅
谷所基行; 白川晃; 植田憲一
Oral presentation, Japanese, レーザー学会,レーザー学会学術講演会第26回年次大会
Feb. 2006

Yb3+添加希土類酸化物セラミックモード同期レーザ
戸倉川正樹; 高市和則; 八木秀喜; 白川晃; 植田憲一; 細川俊介; 柳田高公; A. A. Kaminskii
Oral presentation, Japanese, レーザー学会,レーザー学会学術講演会第26回年次大会
Feb. 2006

Dual-wavelength Laser Performance of Yb:YAG Crystal Grown by Temperature Gradient Technique
Jun Dong; Akira Shirakawa; Ken-ichi Ueda; Jun Xu; Peizhen Deng
Oral presentation, English, Advanced Solid-State Photonics 2006, Lake Taohe
Jan. 2006

2KHz Single Frequency 1083nm Ytterbium Doped MOPA Fiber Laser System
Shenghong Huang; Guanshi Qin; Akira Shirakawa; Mitsuru Musha; Ken-ichi Ueda
Oral presentation, English, Advanced Solid-State Photonics 2006, Lake Taohe
Jan. 2006

2kHz single-frequency Yb-doped fiber MOPA system using dynamic saturable absorption grating loop
Shenghong Huang; Akira Shirakawa; Mitsuru Musha; Ken-ichi Ueda
Oral presentation, English, 21世紀COE第2回合同シンポジウム,21世紀COE第2回合同シンポジウム
Dec. 2005

誘導ラマン散乱を用いた新しいレーザーの開発
高市和則; 植田憲一; A. A. Kaminskii; 八木秀喜; 柳谷高公; P. Becker; L. Bohaty; S. Haussuhl; H. J. Eichler; J. Hanuza; S. N. Bagaev; A. N.Penin
Oral presentation, Japanese, 21世紀COE第2回合同シンポジウム,21世紀COE第2回合同シンポジウム
Dec. 2005

LMA Er:Ybﾌｫﾄﾆｯｸ結晶ﾌｧｲﾊﾞｰと中空ﾌｫﾄﾆｯｸﾊﾞﾝﾄﾞｷﾞｬｯﾌﾟﾌｧｲﾊﾞｰによるﾌｪﾑﾄ秒ﾁｬｰﾌﾟﾊﾟﾙｽ増幅
白川晃; 谷所基行; 植田憲一
Oral presentation, Japanese, 応用物理学会,第66回応用物理学会学術講演会
Sep. 2005

P添加ファイバーラマンレーザーと高非線形ファイバーによる高出力CW超広帯域白色光発生
白川晃; 植田憲一
Oral presentation, Japanese, 応用物理学会,第66回応用物理学会学術講演会
Sep. 2005

1083nm single frequency MOPA fiber laser system
S. Huang; Y. Feng; G. Qin; A. Shirakawa; M. Musha; K. Ueda
Oral presentation, English, 応用物理学会,第66回応用物理学会学術講演会
Sep. 2005

Large-mode-area erbium-ytterbium-doped photonic-crystal fiber amplifier yielding 54-kW femtosecond pulses without chirped-pulse amplification
Akira Shirakawa; Mitsuru Musha; Ken-ichi Ueda; Jacob Riis Folkenberg; Jes Broeng
Oral presentation, English, CLEO-PR/IQEC 2005
Jul. 2005

All-fiber linearly-polarized Yb-doped fiber laser yielding 2.2-W green second harmonics
A. Shirakawa; K. Hiwada; S. Hasegawa; K. Ueda; H. Takuma; K. Mizuuchi; K. Yamamoto; Y. Ochi
Oral presentation, English, CLEO-PR/IQEC 2005
Jul. 2005

Fiber laser coherent array for power scaling, bandwidth narrowing, and coherent beam direction control
Akira Shirakawa; Ken-ichi Ueda
Oral presentation, English, CLEO-PR/IQEC 2005
Jul. 2005

High-power CW supercontinuum generation by phosphosilicate fiber Raman laser and high-nonlinear fiber
Akira Shirakawa; Ken-ichi Ueda
Oral presentation, English, CLEO-PR/IQEC 2005
Jul. 2005

High-power Yb-doped fiber laser directly operating at 1178 nm
Jun Ota; Akira Shirakawa; Ken-ichi Ueda
Oral presentation, English, CLEO-PR/IQEC 2005
Jul. 2005

1083nm single frequency ytterbium fiber laser
Shenghong Huang; Yan Feng; Guanshi Qin; Akira Shirakawa; Mitsuru Musha; Ken-ichi Ued
Oral presentation, English, CLEO-PR/IQEC 2005
Jul. 2005

Limits of coherent addition of lasers: simple estimates
D. Kouznetsov; J-F Bisson; A. Shirakawa; K. Ueda
Oral presentation, English, CLEO-PR/IQEC 2005
Jul. 2005

新しい高出力固体レーザー セラミックレーザーとファイバーレーザー
白川晃; 植田憲一
Oral presentation, Japanese, 特別シンポジウム「横断・融合的学術としての光・光量子科学」, 東京
Apr. 2005

P添加ファイバーラマンレーザーと高非線形ファイバーによる高出力CW超広帯域白色光発生
白川晃; 植田憲一
Oral presentation, Japanese, 第5回レーザー学会東京支部東京支部研究会, 平塚
Mar. 2005

単一偏光Yb店かファイバーレーザーの開発と緑色第二高調波発生
長谷川真吾; 檜皮健二; 太田淳; 白川晃; 植田憲一; 水内公典; 山本和久; 越智雄三
Oral presentation, Japanese, 第5回レーザー学会東京支部東京支部研究会, 平塚
Mar. 2005

LMA Er:Yb共添加フォトニック結晶ファイバーによる高出力フェムト秒パルス増幅
白川晃; 太田淳; 武者満; 植田憲一; J. R. Folkenberg; J. Broeng
Oral presentation, Japanese, 第52回応用物理学関係連合講演会, さいたま
Mar. 2005

単一偏光Ybファイバーレーザーの開発
檜皮健二; 長谷川真吾; 太田淳; 白川晃; 植田憲一; 宅間宏; 水内公典; 山本和久; 越智雄三
Oral presentation, Japanese, 第52回応用物理学関係連合講演会, さいたま
Mar. 2005

複合共振器による高調波モード同期ファイバーレーザー
松尾圭悟; 白川晃; 植田憲一
Oral presentation, Japanese, 第52回応用物理学関係連合講演会, さいたま
Mar. 2005

イッテルビウム添加Lu2O3セラミックレーザー
戸倉川正樹; 高市和則; 八木秀喜; 白川晃; 植田憲一; 細川俊介; 柳谷高公; A. A. Kaminskii
Oral presentation, Japanese, 応用物理学会,第52回応用物理学関係連合講演会
Mar. 2005

Fiber laser coherent array for power scaling, bandwidth narrowing, and beam direction control
Akira Shirakawa; Keigo Matsuo; Ken-ichi Ueda
Oral presentation, English, Advanced Solid-State Photonics 2005, Wien
Feb. 2005

Large-mode-area Er/Yb-doped photonic-crystal fiber amplifier yielding a 40-kW peak power at 1.5 mm
Akira Shirakawa; Jun Ohta; Mitsuru Musha; Ken-ichi Ueda; Jacob Riis Folkenberg; Jes Broeng
Oral presentation, English, Advanced Solid-State Photonics 2005, Wien
Feb. 2005

Large-mode-area erbium-ytterbium-doped photonic-crystal fiber amplifier yielding 54-kW femtosecond pulses without chirped-pulse amplification
Akira Shirakawa; Mitsuru Musha; Ken-ichi Ueda; Jacob Riis Folkenberg; Jes Broeng
Oral presentation, English, Photonics West 2005, San Jose
Jan. 2005

Fiber laser coherent array for power scaling, bandwidth narrowing, and coherent beam direction control
Akira Shirakawa; Keigo Matsuo; Ken-ichi Ueda
Oral presentation, English, Photonics West 2005, San Jose
Jan. 2005

Fiber laser coherent array for power scaling, bandwidth narrowing, and coherent beam direction control
Akira Shirakawa; Keigo Matsuo; Ken-ichi Ueda
Oral presentation, English, Photonics West 2005, Photonics West 2005, San Jose, International conference
Jan. 2005

CW 7-W, 900-nm-wide supercontinuum source by phosphosilicate fiber Raman laser and high-nonlinear fiber
Akira Shirakawa; Ken-ichi Ueda
Oral presentation, English, Photonics West 2005, San Jose
Jan. 2005

高出力ファイバーレーザーの研究
白川晃; 松尾圭悟; 渥美貴之; 太田淳; 檜皮健二; 武者満; 植田憲一
Oral presentation, Japanese, 21世紀COE合同シンポジウム, 調布
Dec. 2004

ファイバーレーザーコヒーレントアレイのビーム方向コヒーレント制御
松尾圭悟; 白川晃; 植田憲一
Oral presentation, Japanese, 第65回応用物理学会学術講演会
Sep. 2004

1178nmYb添加ダブルクラッドファイバーレーザーの開発
太田淳; 白川晃; 植田憲一
Oral presentation, Japanese, 第65回応用物理学会学術講演会, 仙台
Sep. 2004

スペクトロインターフェログラムによる光ファイバの分散測定
渥美貴之; 白川晃; 植田憲一
Oral presentation, Japanese, 第65回応用物理学会学術講演会, 仙台
Sep. 2004

Fiber laser coherent array for power scaling of single-mode fiber laser
Akira Shirakawa; Keigo Matsuo; Ken-ichi Ueda
Oral presentation, English, 5th International Symposium on Laser Precision Microfabrication, Nara
May 2004

Diode-pumped mode-locked Yb3+:Y2O3 ceramic laser
A. Shirakawa; K. Takaichi; H. Yagi; J-F. Bisson; J. Lu; K. Ueda; T. Yanagitani; A. A. Kaminskii
Oral presentation, English, CLEO/IQEC 2004, San Francisco
May 2004

Power summation and bandwidth narrowing in coherently-coupled fiber laser array
Akira Shirakawa; Keigo Matsuo; Ken-ichi Ueda
Oral presentation, English, CLEO/IQEC 2004, San Francisco
May 2004

LD励起モード同期Yb3+:Y2O3セラミックレーザー
白川晃; 高市和則; 八木秀喜; J-F.ビソン; 盧建仁; 植田憲一; 柳谷高公; A.A.カミンスキー
Oral presentation, Japanese, 第51回応用物理学関係連合講演会, 八王子
Mar. 2004

高出力狭帯域ファイバーレーザーコヒーレントアレイ
白川晃; 松尾圭悟; 植田憲一
Oral presentation, Japanese, 第51回応用物理学関係連合講演会, 八王子
Mar. 2004

Fiber laser coherent array for power scaling and bandwidth narrowing
Akira Shirakawa; Keigo Matsuo; Ken-ichi Ueda
Oral presentation, English, Asian Pacific Laser Symposium 2004, Yongpyong, Yongpyong
Feb. 2004

Diode-pumped mode-locked Yb3+:Y2O3 ceramic laser
A. Shirakawa; K. Takaichi; H. Yagi; J-F. Bisson; J. Lu; K. Ueda; T. Yanagitani; A. A. Kaminskii
Oral presentation, English, Asian Pacific Laser Symposium 2004, Yongpyong, Yongpyong
Feb. 2004

Scalable coherent beam coupling of fiber lasers
Akira Shirakawa; Tomoki Sekiguchi; Ken-ichi Ueda
Oral presentation, English, CLEO/Pacific Rim 2003, Taipei, 台北
Dec. 2003

高輝度高出力ファイバーレーザー
白川晃; 植田憲一
Invited oral presentation, Japanese, 平成15年電気学会電子・情報・システム部門大会, 平成15年電気学会電子・情報・システム部門大会
Aug. 2003

高輝度高出力ファイバーレーザー
白川晃; 植田憲一
Oral presentation, Japanese, 平成15年電気学会電子・情報・システム部門大会, 平成15年電気学会電子・情報・システム部門大会
Aug. 2003

ファイバーレーザーのコヒーレントビーム結合のスケーリング
白川晃; 松尾圭悟; 関口知樹; 植田憲一
Oral presentation, Japanese, 第64回応用物理学会学術講演会
Aug. 2003

Scalable coherent beam combining of fiber lasers
Akira Shirakawa; Tomoki Sekiguchi; Ken-ichi Ueda
Oral presentation, English, CLEO/QELS 2003, Baltimore
Jun. 2003

Scalable coherent beam combining of fiber lasers
Akira Shirakawa; Tomoki Sekiguchi; Ken-ichi Ueda
Others, English, Special Seminar, HRL Laboratories
Jun. 2003

Scalable coherent beam combining of fiber lasers
Akira Shirakawa; Tomoki Sekiguchi; Ken-ichi Ueda
Oral presentation, English, 2003 Advanced Solid-State Photonics, San Antonio
Feb. 2003

ファイバーレーザーのコヒーレント結合に関する研究
関口知樹; 白川晃; 武者満; 植田憲一
Oral presentation, Japanese, レーザー学会, 浜松
Jan. 2003

ファイバーレーザーのコヒーレント結合に関する研究
関口知樹; 斉藤智春; 白川晃; 武者満; 植田憲一
Oral presentation, Japanese, 日本光学会, 東京
Nov. 2002

Coherent addition of fiber lasers using a fiber coupler
Akira Shirakawa; Tomoharu Saitou; Tomoki Sekiguchi; Ken-ichi Ueda
Oral presentation, English, 2002 OSA Annual Meeting, Orland
Oct. 2002

ファイバーレーザーのコヒーレント加算に関する研究
関口知樹; 斉藤智春; 白川晃; 武者満; 植田憲一
Oral presentation, Japanese, レーザー学会第302回研究会
Sep. 2002

レーザーダイオードのコヒーレント加算
関口知樹; 斉藤智春; 白川晃; 植田憲一
Oral presentation, Japanese, 第63回応用物理学会学術講演会, 新潟
Sep. 2002

Output-Port Selectable Coherent Addition of Fiber Lasers
Akira Shirakawa; Tomoharu Saitou; Ken-ichi Ueda
Oral presentation, English, International Quantum Electronics Conference 2002, Moscow
Jun. 2002

方向性結合器を用いたコヒーレントファイバーアレイレーザー
白川晃; 斉藤智春; 植田憲一
Oral presentation, Japanese, 第49回応用物理学関係連合講演会
Mar. 2002

Characteristics of a fiber arrayed laser by using a directional fiber coupler
Tomoharu Saitou; Akira Shirakawa; Ken-ichi Ueda
Oral presentation, English, CRL International Symposium
Mar. 2002

方向性結合器を用いたファイバーアレイレーザーの特性
斉藤智春; 白川晃; 谷口篤; 植田憲一
Oral presentation, Japanese, レーザー学会学術講演会第22回年次大会
Jan. 2002

非平行光パラメトリック増幅による可視・近赤外域超短パルス発生
白川晃
Invited oral presentation, Japanese, 第62回応用物理学会学術講演会, 第62回応用物理学会学術講演会
Sep. 2001

非平行光パラメトリック増幅による可視・近赤外域超短パルス発生
白川晃
Invited oral presentation, Japanese, 第62回応用物理学会学術講演会
Sep. 2001

高出力ファイバレーザが持つ無限の可能性
白川晃
Oral presentation, Japanese, 2001年秋季精密工学会
Sep. 2001

高出力ファイバレーザが持つ無限の可能性
白川晃
Oral presentation, Japanese, 2001年秋季精密工学会, 2001年秋季精密工学会
Sep. 2001

最先端のフェムト秒レーザー：光ファイバーレーザーの未来形態
白川晃
Oral presentation, Japanese, ナノフォトニクスシンポジウム
May 2001

最先端のフェムト秒レーザー：光ファイバーレーザーの未来形態
白川晃
Oral presentation, Japanese, ナノフォトニクスシンポジウム, ナノフォトニクスシンポジウム
May 2001

Sub-9-fs pulse generation tunable in visible（550-700nm）and near-IR（0.9-1.3?m）by noncollinear phase-matching and pulse-front matching
A. Shirakawa
Oral presentation, Japanese, CLEO/Pacific Rim '99, Seoul
Sep. 1999

Sub-9-fs pulse generation tunable in visible（550-700nm）and near-IR（0.9-1.3?m）by noncollinear phase-matching and pulse-front matching
A. Shirakawa
Oral presentation, Japanese, CLEO/Pacific Rim '99, Seoul, CLEO/Pacific Rim '99, Seoul, International conference
Sep. 1999

Novel Sub-5-fs Pulse Generation by Noncollinear Optical Parametric Amplification
A. Shirakawa
Oral presentation, Japanese, Sixth International Workshop on Femtosecond Technology, Tsukuba
Jul. 1999

Novel Sub-5-fs Pulse Generation by Noncollinear Optical Parametric Amplification
A. Shirakawa
Invited oral presentation, Japanese, Sixth International Workshop on Femtosecond Technology, Tsukuba
Jul. 1999

Sub-5-fs pulse generation using noncollinear optical parametric amplifier
A. Shirakawa
Oral presentation, Japanese, The memorial symposium of the 25th anniversary of NICTL RAN, Shatura
Jun. 1999

Sub-5-fs pulse generation using noncollinear optical parametric amplifier
A. Shirakawa
Oral presentation, Japanese, The memorial symposium of the 25th anniversary of NICTL RAN, Shatura, The memorial symposium of the 25th anniversary of NICTL RAN, Shatura, International conference
Jun. 1999

Sub-5-fs Visible Pulse Generation by Pulse-front-matched Optical Parametric Amplification
A. Shirakawa; I. Sakane; M. Takasaka; T. Kobayashi
Invited oral presentation, Japanese, CLEO/QELS 1999, Baltimore, CLEO/QELS 1999, Baltimore, International conference
May 1999

Sub-5-fs Visible Pulse Generation by Pulse-front-matched Optical Parametric Amplification
A. Shirakawa; I. Sakane; M. Takasaka; T. Kobayashi
Invited oral presentation, Japanese, CLEO/QELS 1999, Baltimore, International conference
May 1999

応用電磁気学
The University of Electro-Communications

光工学実験第一（木曜）
The University of Electro-Communications

光工学実験第一（木曜）
電気通信大学

電磁気学および演習
The University of Electro-Communications

電磁気学および演習
電気通信大学

応用電磁気学
The University of Electro-Communications

応用電磁気学
電気通信大学

光エレクトロニクス実験第一
The University of Electro-Communications

光エレクトロニクス実験第一
電気通信大学

基礎電磁気学および演習
The University of Electro-Communications

光工学実験第一
The University of Electro-Communications

光工学実験第一
電気通信大学

基礎電磁気学および演習
The University of Electro-Communications

基礎電磁気学および演習
電気通信大学

May 1999 - Present
レーザー学会

Apr. 1999 - Present
Optical Society of America

Apr. 1995 - Present
応用物理学会

The International Society for Optical Engineering

電気学会

High energy femtosecond light source by phase-locked mode-locked multicore fiber laser
白川 晃
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, The University of Electro-Communications, Grant-in-Aid for Scientific Research (B), 22H01985
Apr. 2022 - Mar. 2025

新設計マルチコアファイバーによる自己収束限界を超える高出力反位相モード光発生
白川晃
Principal investigator
2018 - 2020

時間領域モード選択によるマルチコアファイバーレーザーの位相同期モード同期の研究
白川晃
Principal investigator
2014 - 2017

超短パルスレーザーのコヒーレントビーム結合の研究
白川 晃; TUENNERMANN HENRIK; TUENNERMANN Henrik
日本学術振興会, 科学研究費助成事業, 電気通信大学, 特別研究員奨励費, １．超短パルスの分割パルスファイバー増幅器(DPA)を構築した。結合器にはピストン位相差を補償できる能動型とし、増幅ファイバーは偏波保持Yb添加ファイバーを用いた。周波数分解光ゲート法(FROG)により２分割した各パルスのスペクトル位相を計測し、小信号増幅条件下でも増幅ファイバーの異方性の影響により高次分散に差が生じることを示し、計算した結合効率の低下分を実験と比較した。実際の実験で分割パルスのモード不整合により生じる結合効率の低下に比べ、十分小さいことを明らかにした。 ２．光学遅延路による超短パルスモード同期レーザーの時間領域パルス加算法を考案した。モード同期パルス列の偏光を位相変調器によりパルス毎に交代させ、光学遅延路を経て次パルスに結合させることで繰り返し周波数低減を行い、パルスエネルギー・ピークパワーを増大させる。47MHzのフェムト秒Er添加ファイバーレーザーを用い23.5MHzに分周しパルス加算を実証した。 ３．自己収束効果を取り入れたマルチコアファイバー中の非線形伝搬の数値計算結果から、交代位相モードは安定でコア数スケーリングできることを明らかにした。実際にYb添加7コアマルチコアファイバーを用いて交代位相モード選択励振を行った。また開発したMCF中の非線形伝搬のシミュレーションプログラムを用いて実際のファイバーのコア径の不均一性による影響を明らかにした。, 14F03906
25 Apr. 2014 - 31 Mar. 2016

フォトニックバンドギャップ及びマルチコアによるファイバー高エネルギーパルス光源
白川晃
Principal investigator
2013 - 2015

Yb添加フォトニックバンドギャップファイバーによる高効率高出力橙色光源の研究
2009 - 2011

フェムト秒Yb添加セラミックレーザー光源の最短パルス高強度化研究
植田憲一
2008 - 2010

大出力高繰り返し超短パルスYb添加セラミックレーザーおよび増幅器の研究開発
植田憲一
2005 - 2007

オフセット位相同期レーザーアレイによる超短パルス合成の研究
2005 - 2006

複合共振器によるレーザーアレイのコヒーレント制御の研究
2003 - 2005

高出力フェムト秒Yb3+:Y2O3セラミックレーザーの開発
植田憲一
2002 - 2004

光パラメトリック増幅による可視域極超短光パルス発生とJ会合体の超高速ダイナミクス
白川 晃
日本学術振興会, 科学研究費助成事業, 東京大学, 特別研究員奨励費, 98J03750
1998 - 1998

ファイバレーザ装置
Patent right, 白川晃, 植田憲一, 菅博文, 宮島博文, 特願2002-18182, Date applied: 21 Jun. 2002, 浜松ホトニクス(株)，植田憲一，白川晃, 特許4316840, Date issued: 29 May 2009

レーザ着火装置
Patent right, 上木正聡, 植田憲一, 白川晃, 特願2008-029981, Date applied: 12 Feb. 2008, 日本特殊陶業(株)，電気通信大学

今井浩文，白川晃，植田憲一
Patent right, 今井浩文, 白川晃, 植田憲一, 特願2007-211728, Date applied: 15 Aug. 2007, 新日本製鐵(株)・電気通信大学

利得フォトニック結晶光ファイバー、レーザー増幅システム、及び利得フォトニック結晶光ファイバーの設定方法
Patent right, 特願2007-210318, Date applied: 10 Aug. 2007, 白川晃，鈴木博之，谷所基之，植田憲一

Fiber Laser Unit
Patent right, A. Shirakawa, K. Ueda, H. Kan, H. Miyajima, -, Hamamatsu Photonics Co.Ltd., A. Shirakawa, K. Ueda, EU Patent 1517413, Date issued: 22 Nov. 2006

ファイバレーザ
Patent right, 水内公典, 山本和久, 古屋博之, 白川晃, 植田憲一, 特願2005-356288, Date applied: 09 Dec. 2005, 松下電器産業(株)，電気通信大学