Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
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：32.29(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.
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：68.28(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：83.86(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.
Nishioka, Hajime*; Kawanaka, Junji
Hikari Araiansu, 14(11), p.21 - 25, 2003/11
no abstracts in English
Kawanaka, Junji; Yamakawa, Koichi; Nishioka, Hajime*; Ueda, Kenichi*
Optics Letters, 28(21), p.2121 - 2123, 2003/11
Times Cited Count：87 Percentile：93.43(Optics)no abstracts in English
crystal at low temperatureKawanaka, Junji; Yamakawa, Koichi; Nishioka, Hajime*; Ueda, Kenichi*
Optics Express (Internet), 10(10), p.455 - 460, 2002/05
Times Cited Count：48 Percentile：84.26(Optics)no abstracts in English
Kawanaka, Junji; Yamakawa, Koichi; Nishioka, Hajime*; Ueda, Kenichi*
Proceedings of Conference on Lasers and Electro-Optics / Quantum Electronics and Laser Science Conference (CLEO/QELS 2002), p.CPDC8_1 - CPDC8_3, 2002/00
no abstracts in English
Kawanaka, Junji; Nishioka, Hajime*; Inoue, Norihiro*; Ueda, Kenichi*
Applied Optics, 40(21), p.3542 - 3546, 2001/07
Times Cited Count：57 Percentile：89.10(Optics)no abstracts in English
Kawanaka, Junji; Nishioka, Hajime*; Inoue, Norihiro*; Kubota, Yoshinori*; Ueda, Kenichi*
XIII International Symposium on Gas Flow and Chemical Lasers and High-Power Laser Conference (Proceedings of SPIE Vol.4184) (CD-ROM), 4 Pages, 2000/09
no abstracts in English
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.
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.
Ogawa, Kanade; Aoyama, Makoto; Akahane, Yutaka; Tsuji, Koichi; Harimoto, Tetsuo*; Kawanaka, Junji*; Nishioka, Hajime*; Fujita, Masayuki*; Yamakawa, Koichi
no journal, ,
We demonstrated ultra-broadband optical parametric chirped-pulse amplification using a picosecond broadband pump beam at a 1m wavelength region. Using two broadband pump beams, an amplification bandwidth of more than 350 nm was achieved in a type-I BBO crystal with a gain of 3.2
10.
Ogawa, Kanade; Aoyama, Makoto; Akahane, Yutaka; Tsuji, Koichi; Sueda, Keiichi*; Kawanaka, Junji*; Nishioka, Hajime*; Fujita, Masayuki*; Yamakawa, Koichi
no journal, ,
We have demonstrated ultra-broadband optical parametric chirped-pulse amplification of more than 500-nm bandwidth pumped by a diode-pumped, cryogenic-cooled Yb:YLF chirped-pulse amplification laser.
Akahane, Yutaka; Aoyama, Makoto; Ogawa, Kanade; Tsuji, Koichi; Tokita, Shigeki*; Kawanaka, Junji*; Nishioka, Hajime*; Yamakawa, Koichi
no journal, ,
no abstracts in English
Akahane, Yutaka; Aoyama, Makoto; Ogawa, Kanade; Tsuji, Koichi; Tokita, Shigeki*; Kawanaka, Junji*; Nishioka, Hajime*; Yamakawa, Koichi
no journal, ,
A diode-pumped Yb:YAG regenerative amplifier utilizing gain-narrowing has been developed. A chirped-seed pulse was amplified and compressed in the regenerative amplifier, simultaneously, which generated the picosecond pulses with 8 mJ of energy without a pulse compressor.
) chirped-pulse regenerative amplifierAoyama, Makoto; Ogawa, Kanade; Akahane, Yutaka; Tsuji, Koichi; Tokita, Shigeki*; Kawanaka, Junji*; Nishioka, Hajime*; Yamakawa, Koichi
no journal, ,
no abstracts in English
Akahane, Yutaka; Aoyama, Makoto; Ogawa, Kanade; Tsuji, Koichi; Harimoto, Tetsuo*; Kawanaka, Junji*; Nishioka, Hajime*; Fujita, Masayuki*; Yamakawa, Koichi
no journal, ,
no abstracts in English
Ogawa, Kanade; Aoyama, Makoto; Akahane, Yutaka; Tsuji, Koichi; Harimoto, Tetsuo*; Kawanaka, Junji*; Nishioka, Hajime*; Fujita, Masayuki*; Yamakawa, Koichi
no journal, ,
We have demonstrated ultra-broadband optical parametric chirped-pulse amplification of more than 550 nm bandwidth in the near-infrared region. We have observed a substantial enhancement (over 2-fold) of the parametric amplification bandwidth by using time-delayed two broadband pump pulses at degeneracy.
