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Nakajima, Kyo*; Teramoto, Takahiro*; Akagi, Hiroshi; Fujikawa, Takashi*; Majima, Takuya*; Minemoto, Shinichiro*; Ogawa, Kanade*; Sakai, Hirofumi*; Togashi, Tadashi*; Tono, Kensuke*; et al.
Scientific Reports (Internet), 5, p.14065_1 - 14065_11, 2015/09
Times Cited Count：38 Percentile：82.65(Multidisciplinary Sciences)We report on the measurement of deep inner-shell 2p X-ray photoelectron diffraction (XPD) patterns from laser-aligned I
molecules using X-ray free-electron laser (XFEL) pulses. The XPD patterns of the I molecules, aligned parallel to the polarization vector of the XFEL, were well matched with our theoretical calculations. Further, we propose a criterion for applying our molecular-structure-determination methodology to the experimental XPD data. In turn, we have demonstrated that this approach is a significant step toward the time-resolved imaging of molecular structures.
Tomizawa, Hiromitsu*; Sato, Takahiro*; Ogawa, Kanade*; Togawa, Kazuaki*; Tanaka, Takatsugu*; Hara, Toru*; Yabashi, Makina*; Tanaka, Hitoshi*; Ishikawa, Tetsuya*; Togashi, Tadashi*; et al.
High Power Laser Science and Engineering, 3, p.e14_1 - e14_10, 2015/04
Times Cited Count：8 Percentile：41.23(Optics)no abstracts in English
Ogawa, Kanade*; Sato, Takahiro*; Matsubara, Shinichi*; Okayasu, Yuichi*; Togashi, Tadashi*; Watanabe, Takahiro*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; et al.
Proceedings of 10th Conference on Lasers and Electro-Optics Pacific Rim and 18th OptoElectronics and Communications Conference and Photonics in Switching 2013 (CLEO-PR & OECC/PS 2013) (USB Flash Drive), 2 Pages, 2013/06
no abstracts in English
Togashi, Tadashi*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Yamanouchi, Kaoru*; Hara, Toru*; et al.
Proceedings of Ultrafast Optics IX (CD-ROM), 2 Pages, 2013/03
We have demonstrated free-electron laser radiation seeded by high-order harmonics in the extreme-ultraviolet region. Strong enhancement of the radiation intensity by a factor of 104 was observed with timing control of an electro-optical sampling technique.
Okayasu, Yuichi*; Tomizawa, Hiromitsu*; Matsubara, Shinichi*; Sato, Takahiro*; Ogawa, Kanade*; Togashi, Tadashi*; Takahashi, Eiji*; Minamide, Hiroaki*; Matsukawa, Ken*; Aoyama, Makoto; et al.
Proceedings of 1st International Beam Instrumentation Conference (IBIC 2012) (Internet), 5 Pages, 2012/10
no abstracts in English
Ogawa, Kanade; Akahane, Yutaka; Tsuji, Koichi; Yamakawa, Koichi
Reza Kenkyu, 38(10), p.779 - 783, 2010/10
We have newly designed a grism pair compensator for third-order dispersion in a fiber stretched chirped-pulse amplification system. In a numerical calculation, we have obtained a pedestal-free re-compressed pulse close to the transform-limited pulse using the grism pair. We have experimentally demonstrated a two-fold enhancement of peak intensity and pulse shortening of the compressed pulse with this device.
Akahane, Yutaka; Ogawa, Kanade; Tsuji, Koichi; Aoyama, Makoto; Yamakawa, Koichi
Proceedings of SPIE, Vol.7589, p.75890L_1 - 75890L_8, 2010/02
Times Cited Count：0 Percentile：0.00(Engineering, Biomedical)We have proposed and demonstrated a very simple and robust femtosecond optical-parametric chirped-pulse amplification scheme in which an even order dispersion of an idler pulse is compensated by passing through an identical positive dispersive material used for temporal stretching a signal pulse. By compressing the idler pulses having a negatively chirp in this manner, high power sub-100 fs pulses were successfully obtained with only a transparent glass block used for the stretcher and compressor.
Yamakawa, Koichi; Akahane, Yutaka; Ogawa, Kanade; Aoyama, Makoto
Denki Gakkai Hikari, Ryoshi Debaisu Kenkyukai Shiryo OQD-09-61, p.13 - 16, 2009/09
We have proposed and demonstrated a novel optical-parametric chirped-pulse amplification scheme in which an even order dispersion of an idler pulse is compensated by passing through an identical positive dispersive material used for temporal stretching a signal pulse. By compressing the idler pulses having a negatively chirp in this manner, high power sub-100 fs pulses were successfully obtained with only a transparent glass block used for the stretcher and compressor. A feasible design of real world femtosecond laser systems employing this scheme is also discussed.
Akahane, Yutaka; Ogawa, Kanade; Tsuji, Koichi; Aoyama, Makoto; Yamakawa, Koichi
Applied Physics Express, 2(7), p.072503_1 - 072503_3, 2009/07
Times Cited Count：4 Percentile：18.22(Physics, Applied)We have proposed and demonstrated a very simple and robust femtosecond optical-parametric chirped-pulse amplification scheme in which an even order dispersion of an idler pulse is compensated by passing through an identical positive dispersive material used for temporal stretching a signal pulse. By compressing the idler pulses having a negatively chirp in this manner, high power sub-100 fs pulses were successfully obtained with only a transparent glass block used for the stretcher and compressor. A feasible design of real world femtosecond laser systems employing this scheme is also discussed.
Ogawa, Kanade; Sueda, Keiichi*; Akahane, Yutaka; Aoyama, Makoto; Tsuji, Koichi; Fujioka, Kana*; Kanabe, Tadashi*; Yamakawa, Koichi; Miyanaga, Noriaki*
Optics Express (Internet), 17(10), p.7744 - 7749, 2009/05
Times Cited Count：13 Percentile：53.52(Optics)Using a partially deuterated KDP crystal for an optical parametric amplifier, we demonstrated ultrabroadband optical parametric chirped-pulse amplification of more than 250 nm bandwidth at a center wavelength of 1050 nm. We numerically show how to control the broadband phase matching conditions at different wavelengths to match center wavelengths of suitable broadband seed sources by adjusting the deuteration level in partially deuterated KDP.
Yamakawa, Koichi; Aoyama, Makoto; Akahane, Yutaka; Ogawa, Kanade; Tsuji, Koichi
Reza Kenkyu, 36(9), p.555 - 561, 2008/09
We review progress in the generation of ultrahigh-intensity optical pulses in a few-cycle regime. A design of a Generation of ENergetic Beam Ultimate (GENBU) laser based on optical parametric chirped-pulse amplification, which will be produced a peak power of up to 6-PW with a variable pulse durations ranging from 5-fs to 8-ps is described. Ultra-broadband optical parametric chirped-pulse amplification pumped by a picosecond laser pulse delivered from a diode-pumped, cryogenically-cooled Yb:YLF chirped-pulse amplification laser is also reported.
Ogawa, Kanade; Aoyama, Makoto; Akahane, Yutaka; Tsuji, Koichi; Kawanaka, Junji*; Harimoto, Tetsuo*; Nishioka, Hajime*; Fujita, Masayuki*; Yamakawa, Koichi
Japanese Journal of Applied Physics, 47(6), p.4592 - 4594, 2008/06
Times Cited Count：8 Percentile：32.79(Physics, Applied)We have demonstrated ultra-broadband optical parametric chirped-pulse amplification of more than 350 nm bandwidth in a near infrared region. We have observed a substantial enhancement (nearly 2-fold) of the parametric amplification bandwidth by using time delayed two broadband pump pulses at degeneracy.
crystalAkahane, Yutaka; Aoyama, Makoto; Sugiyama, Akira; Kubo, Ryoichi; Ogawa, Kanade; Tsuji, Koichi; Yamakawa, Koichi
Optics Letters, 33(5), p.494 - 496, 2008/03
Times Cited Count：2 Percentile：14.44(Optics)A diode-pumped, cryogenically-cooled Yb:LuLiF regenerative amplifier has been developed for the first time to our knowledge. A chirped-seed pulse was amplified and compressed in the regenerative amplifier, simultaneously, which generated 
6-mJ, 13-ps pulses at 999 nm wavelength without a pulse compressor. Simultaneous lasing at 999 nm and 1024 nm, respectively, was demonstrated, which could be used for different frequency generation in the THz region.
Ogawa, Kanade; Akahane, Yutaka; Harimoto, Tetsuo*; Aoyama, Makoto; Tsuji, Koichi; Kawanaka, Junji*; Nishioka, Hajime*; Fujita, Masayuki*; Yamakawa, Koichi
Reza Kenkyu, 35(9), p.596 - 598, 2007/09
no abstracts in English
) chirped-pulse regenerative amplifierOgawa, Kanade; Akahane, Yutaka; Aoyama, Makoto; Tsuji, Koichi; Tokita, Shigeki*; Kawanaka, Junji*; Nishioka, Hajime*; Yamakawa, Koichi
Optics Express (Internet), 15(14), p.8598 - 8602, 2007/07
Times Cited Count：22 Percentile：68.83(Optics)Ytterbium (Yb
) doped gain media are one of promising laser materials for the next generation of diode-pumped high-power lasers. Yb-doped media have several advantages. It has wide absorption bandwidth, the low quantum defect, and the simple electronic structure. Yb:KY(WO) (Yb:KYW) and Yb:KG(WO) (Yb:KGW) have a large absorption and wide emission cross section, broad emission spectral range, and high thermal conductivity, yielding a high repetition-rate, high-energy, sub-picosecond pulses. However, multi-millijoule-class Yb:KYW or Yb:KGW lasers have not yet been reported so far, excepting a massive, joule-class Ti:sapphire laser pumped Yb:KGW regenerative amplifier. So, We developed a compact diode-pumped, cryogenically-cooled chirped-pulse Yb:KYW regenerative amplifier. An amplified pulse with an energy of 5.5 mJ and a high optical conversion efficiency of 14% is achieved. Regenerative pulse shaping is also used to counter gain narrowing during amplification.
Akahane, Yutaka; Aoyama, Makoto; Ogawa, Kanade; Tsuji, Koichi; Tokita, Shigeki*; Kawanaka, Junji*; Nishioka, Hajime*; Yamakawa, Koichi
Optics Letters, 32(13), p.1899 - 1901, 2007/07
Times Cited Count：42 Percentile：84.31(Optics)A diode-pumped, cryogenic-cooled Yb:YAG regenerative amplifier utilizing gain-narrowing has been developed. A 1.2-ns chirped-seed pulse was amplified and compressed in the regenerative amplifier, simultaneously, which generated a 35-ps pulse with 8-mJ of energy without a pulse compressor. Second-harmonics of the amplified pulse was used to pump picosecond two-color optical parametric amplification.
Aoyama, Makoto; Akahane, Yutaka; Ogawa, Kanade; Tsuji, Koichi; Sugiyama, Akira; Harimoto, Tetsuo*; Kawanaka, Junji*; Nishioka, Hajime*; Fujita, Masayuki*; Yamakawa, Koichi
Reza Kenkyu, 35(6), p.398 - 399, 2007/06
We have demonstrated optical parametric chirped-pulse amplification by using a diode-pumped Yb:YLF CPA laser system as a pump source and achieved an ultra-broadband amplification of over 200-nm supporting a 12.6-fs duration (3.7 optical cycles) in spite of being operated around degeneracy. By using a two-stage OPCPA with a higher-energy pump pulse, it should be able to produce a terawatt-class, few-cycle laser pulse without complexly and enlarging the system size. Such a laser is useful for the generation of attosecond pulse generation in the xuv region as well as other high field applications.
Akahane, Yutaka; Aoyama, Makoto; Ogawa, Kanade; Tsuji, Koichi; Sugiyama, Akira; Yamakawa, Koichi; Kawanaka, Junji*; Harimoto, Tetsuo*; Nishioka, Hajime*; Fujita, Masayuki*
no journal, ,
We have confirmed ultra-broadband optical-parametric amplification (OPA) over 200 nm pumped by one beam of Yb:YLF CPA laser at degeneracy. A white light seed pulse with a bandwidth of 400 nm is generated by the 80-fs duration mode-locked pulse, that was identical to seed pulse for the Yb:YLF CPA pump laser, through a photonic crystal fiber, and then temporally stretched to -2 ps by passing through a glass block and injected to the BBO crystal at an internal crossing angle of 0.6 degree. The pump pulse with 3ps pulse duration was down-collimated and used to pump the crystal with an energy of 1.1 mJ. As a result, we have observed an ultra-broadband amplification over 200nm. The OPA gain was measured to be -10
, which corresponds to sub-100 
J energy of amplified signal pulse. With injecting second pump pulse with a different internal crossing angle of 1.2 degree, our OPCPA could amplify the 400 nm bandwidth which supports the intense few-cycle pulse generation.
Akahane, Yutaka; Aoyama, Makoto; Ogawa, Kanade; Tsuji, Koichi; Kawanaka, Junji*; Nishioka, Hajime*; Fujita, Masayuki*; Yamakawa, Koichi
no journal, ,
White-light seed pulse for few-cycle optical-parametric chirped-pulse amplification system have been generaged by focusing 80-fs laser pulse from mode-locked oscillator. There were large gaps in the spectral phase of previous white-light generated with photonic-crystal fiber (PCF) for its high-nonlinearity, which limits the minimum compressed pulse duration to 20-30 fs even with adaptive phase control. In this study the white-light was generated by self-phase moduration induced from focusing ultrashort laser pulse on optical substrates. In the experiment, oscillator output pulses with 80-fs duration and 1021 nm center wevelength were parametric-amplified by second harmonics of Yb:YLF CPA system in advance, and focused on optical substrates by microscope objective lens. As a result, broadband white-light pulses from 700 to 1200 nm were generated with 10
-10
intensity ratio, which is sufficient for seed pulse for ultrabroadband OPCPA.
Aoyama, Makoto; Akahane, Yutaka; Tsuji, Koichi; Ogawa, Kanade; Harimoto, Tetsuo*; Kawanaka, Junji*; Nishioka, Hajime*; Fujita, Masayuki*; Yamakawa, Koichi
no journal, ,
no abstracts in English
