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Recent topics on the engineering for solid-state peak-power lasers in repetitive operation
Masahiro Nakatsuka,Hidetsugu Yoshida,Hisanori Fujita,Kana Fujioka,Yasushi Fujimoto,Yasushi Fujimoto 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.43 No.42
Solid-state lasers have been developed for peak-power operation in the terawatt to petawatt regions by using chirped pulse amplication (CPA) and optical parametric (OPCPA) technology. Also thermal distortion-free, 10-nsec repetitive peak-power lasers have been developed. Broadband amplication of a solid-state laser is a key issue for the pre-amplication stage of CPA system, and the OPA scheme gives a high gain with a very low pre-pulse level while keeping a 5-nm bandwidth. On the other hand, nonlinear optical technology using stimulated Brillouin scattering (SBS) is promising as a way to compensate for thermal diculties caused in strongly pumped laser materials. SBS is well known for the phase conjugation mirror (PCM) used for an average power output with a high re ectivity of over 95 %. A liquid uorocarbon with a special treatment can be used to achieve a 10-ns duration, 50-Hz repetition laser delivering 0.4-GW peak power, with a 200-W average power. A liquid ow system in an SBS cell can be used to realize PCM behavior up to the kW range. The last theme in this paper is a short review of new ceramic materials for a scalable solid-state laser. In past ten years, Japanese researchers have investigated new transparent ceramic YAG materials for industrial application. The ceramics have many advantages for an average power laser, such as high doping rate, co-doping potential, large-size fabrication, and composite structure.
공홍진,Dong Won Lee,Jin Woo Yoon,Masahiro Nakatsuka,Seong Ku Lee 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.III
For practical laser fusion energy (IFE) generation, a M-J laser driver is required with a repetition rate of over 10 Hz. Achieving an IFE driver with this high repetition rate requires reduction of the thermal load of the laser system. Several methods have been developed for this goal, such as beam combination, the gas-cooled, diode-pumped laser, the electron beam pumped gas laser, and the large-sized ceramic Nd:YAG. The beam-combination technique using stimulated Brillouin scattering phase conjugate mirrors (SBS-PCM) is a promising one among these techniques for the IFE driver. The beam-combination laser system does not need a large-gain medium, so it can be operated at a repetition rate exceeding 10 Hz, regardless of the output energy. Moreover, it is easily adaptable to the modern laser technology. We propose a beam-combination laser with SBS-PCMs whose energy can be freely scaled up by increasing the number of separate amplifiers, and also demonstrate the practical and efficient phase control of SBS waves which is essential in a beamcombination laser using SBS-PCMs. In this paper, recent theoretical and experimental results on phase control and a beam-combination laser for developing the IFE driver are discussed in detail.p
Bismuth-Doped Silica Glass as a New Laser Material
Young-Seok Seo,Changhwan Lim,Masahiro Nakatsuka,Yasushi Fujimoto 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.I
The excellent thermal and mechanical properties of silica glass are very attractive for a high-average-power laser medium. We have been developing a new laser medium based on silica glass, and we have discovered a new infrared emission from a bismuth-doped silica glass. Also, we achieved an optical amplification in a bismuth-doped silica fiber at 1308 nm with an 810-nm excitation.
YOSHIDA, Hidetsugu,NAGASAWA, Muneyuki,OKADA, Hajime,FUJITA, Hisanori,NAKATSUKA, Masahiro,PARKS, Hyunmin レーザー學會 2008 レーザー硏究 Vol.36 No.9
Heavy fluorocarbons and perfluoropolyether liquids are ideal media for high power stimulated Brillouin scat-tering experiments from ultraviolet to infrared laser. Stimulated Brillouin scattering (SBS) reflectivity and threshold of new SBS liquids were measured systematically at four wavelengths (1064, 532, 355 and 266 nm). Fluorinert FC-72, -75, -77 and Galden HT 70, -135 exhibits high reflectivity of over 90 % and excellent fidel-ity in phase conjugation for over 100 mJ, 10 ns optical pulse at 1064, 532, and 355 run. Among them, FC-77 and HT 70 were found to be good candidates to replace FC-72, -75 liquids which previously were known to be a good SBS media up to now. Heavy fluorocarbons and perfluoropolyether liquids are most promising as a phase conjugate SBS mirror for all solid-state high-energy lasers because of its high damage threshold and low absorbance.
9.6 dB Gain at a 1310 nm Wavelength for a Bismuth-doped Fiber Amplifier
Seo, Young-Seok,Lim, Chang-Hwan,Fujimoto, Yasushi,Nakatsuka, Masahiro Optical Society of Korea 2007 Current Optics and Photonics Vol.11 No.2
A 9.6 dB gain is observed at 1310 nm in a 5.0 cm bismuth-doped silica fiber. A launched pump power of 100 mW was obtained using an 810-nm laser diode. We demonstrated the simultaneous optical amplification at two wavelengths near second telecommunication windows, which is the range of zero-dispersion for silica fibers.