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Yogo, Akifumi*; Bulanov, S. V.; Mori, Michiaki; Ogura, Koichi; Esirkepov, T. Z.; Pirozhkov, A. S.; Kanasaki, Masato*; Sakaki, Hironao; Fukuda, Yuji; Bolton, P.; et al.
Plasma Physics and Controlled Fusion, 58(2), p.025003_1 - 025003_7, 2016/02
Times Cited Count：9 Percentile：46.03(Physics, Fluids & Plasmas)Kiriyama, Hiromitsu; Mori, Michiaki; Pirozhkov, A. S.; Ogura, Koichi; Sagisaka, Akito; Kon, Akira; Esirkepov, T. Z.; Hayashi, Yukio; Kotaki, Hideyuki; Kanasaki, Masato*; et al.
IEEE Journal of Selected Topics in Quantum Electronics, 21(1), p.1601118_1 - 1601118_18, 2015/01
Times Cited Count：60 Percentile：95.3(Engineering, Electrical & Electronic)This paper reviews the development of a high-contrast high-intensity petawatt-class Ti:sapphire chirped-pulse amplification (CPA) laser for research on high field science. We discuss in detail the design, performance and characterization of the laser. We also describe the on-going upgrade of the laser system and some applications for the laser in relativistic dominated laser-matter interactions.
Ledingham, K.*; Bolton, P. R.*; Shikazono, Naoya; Ma, C.-M.*
Applied Sciences (Internet), 4(3), p.402 - 443, 2014/09
Times Cited Count：90 Percentile：89.45(Chemistry, Multidisciplinary)Kiriyama, Hiromitsu; Mori, Michiaki; Suzuki, Masayuki*; Daito, Izuru*; Okada, Hajime; Ochi, Yoshihiro; Tanaka, Momoko; Sato, Masatoshi*; Tamaoki, Yoshinori*; Yoshii, Takehiro*; et al.
Reza Kenkyu, 42(6), p.441 - 447, 2014/06
We describe three specific high power laser systems that are being developed in our laboratory for many applications in high field science, nonlinear optics and material processing. We report on a femtosecond petawatt-class Ti:sapphire chirped-pulse amplification laser system that can produce a pulse energy of 20 J of 40 fs pulse duration, a picosecond high intensity Yb:YAG chirped-pulse amplification laser system that can generate a pulse energy of 100 mJ of 0.5 ps pulse duration, and a nanosecond high repetition rate Nd:YAG laser system that can provide an average power of 360 W with a pulse duration of 30 ns delivered at a 1 kHz repetition rate. We discuss the basic design aspects and present the results from our experimental investigations of these laser systems.
Bolton, P.; Borghesi, M.*; Brenner, C.*; Carroll, D. C.*; De Martinis, C.*; Fiorini, F.*; Flacco, A.*; Floquet, V.*; Fuchs, J.*; Gallegos, P.*; et al.
Physica Medica; European Journal of Medical Physics, 30(3), p.255 - 270, 2014/05
Times Cited Count：77 Percentile：88.84(Radiology, Nuclear Medicine & Medical Imaging)Kiriyama, Hiromitsu; Mori, Michiaki; Okada, Hajime; Shimomura, Takuya; Nakai, Yoshiki*; Tanoue, Manabu; Kondo, Shuji; Kanazawa, Shuhei; Yogo, Akifumi; Sagisaka, Akito; et al.
JPS Conference Proceedings (Internet), 1, p.015095_1 - 015095_5, 2014/03
We present the design and characterization of a high-contrast, petawatt-class Ti:sapphire chirped-pulse amplification (CPA) laser system. Two saturable absorbers and low-gain optical parametric chirped-pulse amplification (OPCPA) preamplifier in the double CPA laser chain have improved the temporal contrast to 1.4
10
on the subnanosecond time scale at 70 terawatt level. Final uncompressed broadband pulse energy is 28 J, indicating the potential for reaching peak power near 600 terawatt. We also discuss our upgrade to over petawatt level at a 0.1 Hz repetition rate briefly.
Mori, Michiaki; Kando, Masaki; Kotaki, Hideyuki; Hayashi, Yukio; Kiriyama, Hiromitsu; Okada, Hajime; Pirozhkov, A. S.; Bulanov, S. V.; Kondo, Kiminori; Bolton, P.
JPS Conference Proceedings (Internet), 1, p.015094_1 - 015094_6, 2014/03
We report on the appropriate and inappropriate gas materials to generate energetic electrons. The 4-TW peak power and 40-fs pulse duration laser beam illuminated the gas-jet target with intensity of 910
W/cm
measured in vacuum. We investigated energetic electron beam generation using neon and argon. Energetic electron beam was observed in argon at the lowest neutral gas density of 510
cm
. However, no energetic electrons (
1 MeV, 1 pC) were observed in neon although neutral gas density is increased from510cm to 510
cm. By considering ionization stage at such an intensity, the maximum plasma density is reached to be a quarter critical plasma density, at which the maximum growth-rate of laser-plasma instability is expected. On the other hand, propagation of the pumping laser was observed in neon and argon by using optical probing. Significantly different images were observed. The structure of the laser channel for energetic electron beam generation that observed in argon was absent in neon. These results imply that the additional increase of the plasma density due to ionization cannot explain the electron generation. The analysis including the propagation of a laser in ionizing gas would be necessary.
Sagisaka, Akito; Pirozhkov, A. S.; Nishiuchi, Mamiko; Ogura, Koichi; Sakaki, Hironao; Yogo, Akifumi; Mori, Michiaki; Kiriyama, Hiromitsu; Okada, Hajime; Kanazawa, Shuhei; et al.
Reza Kenkyu, 42(2), p.160 - 162, 2014/02
High-intensity laser and thin-foil interactions produce high-energy particles, hard X-ray, high-order harmonics, and terahertz radiation. A proton beam driven by a high-intensity laser has received attention as a compact ion source for medical and other applications. We have measured the proton yield from thin-foil targets irradiated with a high-intensity Ti:sapphire laser (J-KAREN) at JAEA. The longitudinal extent of the preformed plasma protruding from the front surface of the target is reduced by decreasing the duration of the amplified spontaneous emission (ASE) before the main pulse. The maximum proton energy in the target normal direction increases when the size of the preformed plasma is controlled.
Yogo, Akifumi; Kondo, Kiminori; Mori, Michiaki; Kiriyama, Hiromitsu; Ogura, Koichi; Shimomura, Takuya; Inoue, Norihiro*; Fukuda, Yuji; Sakaki, Hironao; Jinno, Satoshi; et al.
Optics Express (Internet), 22(2), p.2060 - 2069, 2014/01
Times Cited Count：10 Percentile：49.33(Optics)Kiriyama, Hiromitsu; Shimomura, Takuya; Mori, Michiaki; Nakai, Yoshiki*; Tanoue, Manabu; Kondo, Shuji; Kanazawa, Shuhei; Pirozhkov, A. S.; Esirkepov, T. Z.; Hayashi, Yukio; et al.
Applied Sciences (Internet), 3(1), p.214 - 250, 2013/03
Times Cited Count：15 Percentile：50(Chemistry, Multidisciplinary)This paper reviews techniques for improving the temporal contrast and spatial beam quality in an ultra-intense laser system that is based on chirped-pulse amplification (CPA). We describe the design, performance, and characterization of our laser system, which has the potential for achieving a peak power of 600 TW. We also describe applications of the laser system in the relativistically dominant regime of laser-matter interactions and discuss a compact, high efficiency diode-pumped laser system.
Kiriyama, Hiromitsu; Shimomura, Takuya; Sasao, Hajime; Nakai, Yoshiki*; Tanoue, Manabu; Kondo, Shuji; Kanazawa, Shuhei; Pirozhkov, A. S.; Mori, Michiaki; Fukuda, Yuji; et al.
Optics Letters, 37(16), p.3363 - 3365, 2012/08
Times Cited Count：39 Percentile：85.86(Optics)We demonstrate the temporal contrast enhancement in a petawatt-class Ti:sapphire chirped-pulse amplification (CPA) laser system. An extra saturable absorber, introduced downstream a low gain optical parametric chirped-pulse amplification (OPCPA) preamplifier, has improved the temporal contrast in the system to 1.410 on the sub-nanosecond time scale at 70 TW power level. We have achieved 28 J of uncompressed broadband output energy with this system, indicating the potential for reaching peak powers near 600 TW.
Suzuki, Masayuki; Kiriyama, Hiromitsu; Daito, Izuru; Okada, Hajime; Ochi, Yoshihiro; Sato, Masatoshi*; Yoshii, Takehiro*; Tamaoki, Yoshinori*; Maeda, Junya*; Matsuoka, Shinichi*; et al.
AIP Conference Proceedings 1465, p.53 - 57, 2012/07
Times Cited Count：0 Percentile：0.13(Physics, Applied)We have reported hundred mJ level, femtosecond pulse duration with the high temporal contrast in an OPCPA/Yb:YAG ceramic thin disk laser system at 10 Hz repetition rate. At an input laser pulse energy of 3.8 mJ from the OPCPA preamplifer the output energy of 130 mJ with spectral bandwidth of 2.5 nm has been obtained from multipass Yb:YAG ceramic thin disk amplifier, and the optical efficiency from LD energy to amplified laser pulse is 9.6%. The recompressed laser pulse duration was measured to be 450 fs. Because the compressor efficiency exceeds 73% the compressed pulse energy can potentially be as high as 95 mJ. The contrast level of this laser pulse was measured to be less than 7.210
at -150 ps. This novel laser system after further amplification using additional amplifiers can be useful for the laser-driven proton acceleration in future.
Ogura, Koichi; Nishiuchi, Mamiko; Pirozhkov, A. S.; Tanimoto, Tsuyoshi*; Sagisaka, Akito*; Esirkepov, T. Z.; Kando, Masaki; Shizuma, Toshiyuki; Hayakawa, Takehito; Kiriyama, Hiromitsu; et al.
Optics Letters, 37(14), p.2868 - 2870, 2012/07
Times Cited Count：83 Percentile：95.88(Optics)Using high contrast (10
:1) and high intensity (10
W/cm) laser pulse with the duration of 40 fs from OPCPA/Ti:Sapphire laser, a 40 MeV proton bunch is obtained, which is a record for laser pulse with energy less than 10 J. The efficiency for generation of protons with kinetic energy above 15 MeV is 0.1%.
Pikuz, T.; Faenov, A.*; Fukuda, Yuji; Kando, Masaki; Bolton, P.; Mitorfanov, A.*; Vinogradov, A.*; Nagasono, Mitsuru*; Ohashi, Haruhiko*; Yabashi, Makina*; et al.
Optics Express (Internet), 20(4), p.3424 - 3433, 2012/02
Times Cited Count：27 Percentile：76.85(Optics)Kiriyama, Hiromitsu; Suzuki, Masayuki*; Daito, Izuru; Okada, Hajime; Ochi, Yoshihiro; Sato, Masatoshi*; Tamaoki, Yoshinori*; Yoshii, Takehiro*; Maeda, Junya*; Matsuoka, Shinichi*; et al.
Reza Kenkyu, 40(2), p.143 - 145, 2012/02
We demonstrate a compact, high-spatiotemporal-quality, high-intensity diode-pumped Yb:YAG thin-disk chirped-pulse amplification (CPA) laser system that incorporates a nonlinear preamplifier based on optical parametric chirped-pulse amplification (OPCPA). The stretched pulses are amplified in the OPCPA preamplifier and the following Yb:YAG main amplifier to 
100 mJ at 10 Hz. The broadband amplified beam quality of 1.1 (horizontal direction) and 1.4 (vertical direction) times diffraction limited and pulse compression down to 470 fs with contrast of better than 10
have been achieved successfully.
Imaizumi, Mitsuru*; Yuri, Yosuke; Bolton, P.; Sato, Shinichiro; Oshima, Takeshi
Proceedings of 38th IEEE Photovoltaic Specialists Conference (PVSC-38) (CD-ROM), p.002831 - 002834, 2012/00
High-energy proton irradiation tests were performed on InGaP/GaAs/Ge triple-junction (3J) solar cells with a variety of beam conditions. Irradiation area of about 80 mm 80 mm was achieved by two different techniques, namely, the spot beam scanning and the defocused beam uniformization using multi-pole magnets. Degradation trend of the cells irradiated with the defocused uniform beam under a variety of doze rates exhibited no significant difference compared to the trend irradiated with the scanned beam under a constant dose rate. This result is consistent with our previous fundamental study, and indicates possibility of reduction of irradiation test duration. Irradiation experiment with a multiple energy proton beam is planned, and generation of such proton beam is now under development. Once a proton beam with energy spectrum similar to space environment, a number of irradiation tests with different proton energies and also an energy equivalent fluence calculation using relative damage coefficients or displacement damage dose will be unnecessary.
Suzuki, Masayuki*; Kiriyama, Hiromitsu; Daito, Izuru; Ochi, Yoshihiro; Okada, Hajime; Sato, Masatoshi*; Tamaoki, Yoshinori*; Yoshii, Takehiro*; Maeda, Junya*; Matsuoka, Shinichi*; et al.
Applied Physics B, 105(2), p.181 - 184, 2011/11
Times Cited Count：5 Percentile：28.65(Optics)We have demonstrated an OPCPA/Yb:YAG ceramic thin disk hybrid laser system having hundred mJ level pulse energy sub-picosecond pulse duration with high temporal contrast. At an input energy of 3.8 mJ from an OPCPA preamplifier an output energy of 130 mJ was obtained from Yb:YAG ceramic thin disk amplifier. A recompressed pulse duration of 450 fs with a contrast level of less than 7.210
was obtained. The contrast level is the highest value achieved in Yb:YAG chirped pulse amplification (CPA) laser system with hundred mJ level.
Yogo, Akifumi; Sato, Katsutoshi; Nishikino, Masaharu; Maeda, Takuya*; Sakaki, Hironao; Hori, Toshihiko*; Ogura, Koichi; Nishiuchi, Mamiko; Teshima, Teruki*; Nishimura, Hiroaki*; et al.
Japanese Journal of Applied Physics, 50(10), p.106401_1 - 106401_7, 2011/10
Times Cited Count：8 Percentile：34.67(Physics, Applied)Yogo, Akifumi; Maeda, Takuya; Hori, Toshihiko; Sakaki, Hironao; Ogura, Koichi; Nishiuchi, Mamiko; Sagisaka, Akito; Bolton, P.; Murakami, Masao*; Kawanishi, Shunichi; et al.
Nuclear Instruments and Methods in Physics Research A, 653(1), p.189 - 192, 2011/10
Times Cited Count：9 Percentile：57.01(Instruments & Instrumentation)Fukuda, Yuji; Faenov, A.*; Tampo, Motonobu; Pikuz, T.*; Nakamura, Tatsufumi; Kando, Masaki; Hayashi, Yukio; Yogo, Akifumi; Sakaki, Hironao; Kameshima, Takashi*; et al.
Progress in Ultrafast Intense Laser Science VII, p.225 - 240, 2011/05
http://www.springer.com/physics/atomic,+molecular,+optical+%26+plasma+physics/book/978-3-642-18326-3We present substantial enhancement of the accelerated ion energies up to 10-20 MeV per nucleon by utilizing the unique properties of the cluster-gas target irradiated with 40-fs laser pulses of only 150 mJ energy, corresponding to approximately tenfold increase in the ion energies compared to previous experiments using thin foil targets. A particle-in-cell simulation infers that the high energy ions are generated at the rear side of the target due to the formation of a strong dipole vortex structure in sub-critical density plasmas. The demonstrated method can be important in the development of efficient laser ion accelerators for hadron therapy and other applications.