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Tomoyuki YATSUHASHI, Nobuaki NAKASHIMA
2008 Volume 36 Issue APLS Pages
1000-1003
Published: 2008
Released on J-STAGE: December 25, 2008
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We investigated the direct ionization and desorption of solid C
60 by the irradiation of femtosecond nonresonant (neutral and cationic states) pulses at 1.4 µm. We concluded that ion desorption is induced by Coulomb explosion. Initially formed highly charged molecular ions were annihilated with neighboring neutral or lower-charged ions, which finally resulted in singly charged C
60. The electronically and vibrationally excited hot ions were formed by the release of excess energy after the charge redistribution, electron-hole recombination, and electron impact processes leading to delayed (thermal) ionization. Singly charged ions were finally emitted due to the high density of the surface charge.
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Hidetoshi KATORI, Masao TAKAMOTO, Tomoya AKATSUKA
2008 Volume 36 Issue APLS Pages
1004-1007
Published: 2008
Released on J-STAGE: December 25, 2008
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We report on frequency comparison of two optical lattice clocks based on fermionic
87Sr trapped in 1D optical lattice and bosonic
88Sr in 3D one. We discuss that these two lattice clock configurations would optimize the lattice clocks' performance from the view point of the quantum statistical properties of interrogated atoms and optical lattice geometries. The frequency comparison of two optical clocks offers an important step to investigate the lattice clocks' uncertainty less than 10
-15, where no working standard exists.
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Peixiang LU, Pengfei LAN, Wei CAO, Yiwei HONG, Yuhua LI, Zhenyu YANG
2008 Volume 36 Issue APLS Pages
1008-1011
Published: 2008
Released on J-STAGE: December 25, 2008
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In our work, we propose a scheme for coherent control the HHG with an ultrashort laser pulse in combination with a controlling pulse. It is shown that this method can significantly modulate the electron dynamics and a broadband supercontinuous high harmonics can be generated. Then an isolated sub-100 attosecond pulse can be obtained, which allows one to measure a wide range of ultrafast dynamics not normally accessible before.
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Kazumichi YOSHII, Godai MIYAJI, Kenzo MIYAZAKI
2008 Volume 36 Issue APLS Pages
1012-1015
Published: 2008
Released on J-STAGE: December 25, 2008
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We measured the dependence of high-order harmonic generation (HHG) on the angle α between polarization directions of high-intensity femtosecond laser pulses in the pump and probe experiment. The experimental results of N
2 and O
2 are compared with the calculated ones using the theory developed recently to illustrate the characteristic properties of HHG from aligned N
2 and O
2, and then the excellent agreement is obtained. It is also shown that the observed α-dependent harmonic signal is strongly influenced by the degree of alignment of molecules and is not identical to the harmonic distribution calculated as a function of the angle between the field direction and the molecular axis.
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Peng LIU, Pengfei YU, Zhinan ZENG, Ruxin LI, Zhizhan XU
2008 Volume 36 Issue APLS Pages
1016-1019
Published: 2008
Released on J-STAGE: December 25, 2008
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Angular characteristics of high-order harmonic generation from aligned CO
2 molecules have been investigated. The modulation inversion of harmonic yield with respect to molecular alignment can be altered dramatically by fine tuning the intensity of driving laser pulse for harmonic generation. The result is beyond the two-center quantum interference model and can be modeled by employing the strong field approximation including ground state depletion effect. Laser intensity is found to be a new parameter to control the high harmonic emission from aligned molecules.
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Yasutomo SHIOMI, Takeshi YAMAMOTO, Yuta AOKI, Hiroshi KUMAGAI
2008 Volume 36 Issue APLS Pages
1020-1023
Published: 2008
Released on J-STAGE: December 25, 2008
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Novel optogalvanic spectroscopy of silicon atoms was conducted with the narrow-linewidth nanosecond pulsed deep-ultraviolet coherent light source which was comprised of the frequency-tripled nanosecond pulsed Ti:sapphire laser injection-seeded by another frequency-scanning cw Ti:sapphire laser. Only when the laser frequency of the seed laser matched with the cavity frequency of the slave laser, signals increased remarkably. The individual spectral widths derived from the injection-seeding effect should be the tolerance for successful injection-seeding in the axial mode of the slave laser, and indicated the linewidth of the injection-seeded ns pulsed deep-ultraviolet laser. So the cavity performances of the slave laser can be seen from the spectrum. The envelope of these peaks indicated the absorption spectrum of silicon atoms. This spectral width had the FWHM of 4.8 GHz in the Gaussian fitting and was equivalent to nearly the pure Doppler width, which could not be measured with the system without the injection seeding.
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Sayuri YAMAGUCHI, Satori HIRAI, Kohji IKESHIMA, Motohiro BANNO, Kaoru ...
2008 Volume 36 Issue APLS Pages
1024-1027
Published: 2008
Released on J-STAGE: December 25, 2008
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We have investigated vibrational dynamics of hydrogen-bonded complexes in solutions by sub-picosecond infrared (IR) pump-probe spectroscopy. The anharmonic coupling between the OH stretching mode of benzoic acid dimer and low-frequency mode was studied from analysis of the quantum beat observed in the pump-probe signal. The IR absorption spectrum of 9-fluorenone (FL) in alcohol shows three distinct contributions from the free FL, its complex with one alcohol molecule, and that with two molecules. The time constants of the vibrational energy relaxation (VER) of the CO stretching mode of the free FL and that of the 1:1 complex were obtained. The VER of the OH stretching mode of methanol was studied in the isotopically diluted methanol. The internal isotope effect on the VER is discussed.
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Yusuke FURUKAWA, Momoko TANAKA, Hidetoshi MURAKAMI, Shigeki SAITO, Nob ...
2008 Volume 36 Issue APLS Pages
1028-1030
Published: 2008
Released on J-STAGE: December 25, 2008
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A nickel-like silver laser emitting at 13.9-nm wavelength was used to evaluate the scintillation properties of a hydrothermal method grown zinc oxide (ZnO) crystal in an extreme ultraviolet region. The streak images were used to study the temperature dependence and decay time of the ZnO emission from 25 K to 298 K. Increasing the temperature within this range gradually shifts the emission peak position from 3.32 eV to 3.22 eV. Additionally, its spectrum width in full width at half maximum increases by 0.09 eV from 0.05 eV (at 25 K) to 0.14 eV (at 298 K). Finally, the measured emission decay at 105 K was fitted by a double exponential decay to be τ
1=0.88(4) ns, and τ
2=2.7(2) ns. This decay time of a few nanoseconds is sufficiently short for the characterization of laser plasma EUV sources with nanoseconds duration and is suitable for lithographic applications.
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Kenichi HIROSAWA, Yoshinori MOMOSE, Yuji FUJIWARA, Fumihiko KANNARI, S ...
2008 Volume 36 Issue APLS Pages
1031-1034
Published: 2008
Released on J-STAGE: December 25, 2008
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Photon-number squeezing and quadrature squeezing were studied using ultrafast fibre nonlinear optics pumped by 1.5 µm femtosecond laser pulses. To obtain quadrature squeezing using an Erbium doped fibre amplifiers (EDFA) light source, we developed temporal homodyne technology to exclude the excess noise of an EDFA light source. We also performed a quadrature squeezing experiment using an optical parametric oscillator light source in stead of an EDFA light source exhibiting substantially high excess noise. Although the photon-number squeezing of -3dB was obtained from an asymmetric Sagnac fibre loop, the quadrature noise could not decrease to less than the Shot noise level without cooling the fibre, which is presumably due to GAWBS. To suppress guided acoustic wave Brillouin scattering, we refrigerated the fibre loop by liquid nitrogen, and squeezing at -0.7 dB was obtained by cooling the fiber at liquid nitrogen temperature.
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Fumiyoshi KUWASHIMA, Hiroshi IWASAWA
2008 Volume 36 Issue APLS Pages
1035-1037
Published: 2008
Released on J-STAGE: December 25, 2008
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Effects of the light polarization on a chaotic oscillation dynamics of a single-mode He-Ne(6326Å) class A laser was studied by using optical delayed feedback with an external optical resonator. We observed time series, spectra, phase portraits and Lyapunov exponents for each linear and random polarization lasers.
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Hiromasa ITO, Takefumi HARA, Cheikh NDIAYE
2008 Volume 36 Issue APLS Pages
1038-1041
Published: 2008
Released on J-STAGE: December 25, 2008
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A frequency-shifted feedback laser (FSFL), which generates a comb of chirped frequency components, has the ability for long distance and high accuracy optical ranging. In this report, the principles and performance of an FSFL ranging based on optical frequency-domain ranging are reviewed. This laser system could achieve a high accuracy, and less affected by distance up to range of 1 km. Applications of the FSFL to 3D shape measurement are also described.
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Dafu CUI, Jialin XU, Yong BO, Qianjin CUI, Qinjun PENG, Zuyan XU
2008 Volume 36 Issue APLS Pages
1042-1045
Published: 2008
Released on J-STAGE: December 25, 2008
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The high power all-solid-state red, green and blue lasers have been developed by means of Q-switched diode side-pumped Nd:YAG laser modules and the intracavity nonlinear frequency conversion in the LBO nonlinear crystals. The red laser generates based on the frequency doubled 1.3 µm Nd:YAG transition, and corresponding maximum output power is 64 W. The green output power of 218 W from frequency doubled 1064 nm Nd:YAG transition have been obtained. The blue laser based on the frequency tripled 1.3 µm Nd:YAG transition delivers the output power of 7.6 W. To best of our knowledge, this is the maximum blue output power for the intracavity frequency tripled 1319 nm Nd:YAG laser.
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Toshifumi YOKOYAMA, Kenji NAKAYAMA, Akira KUROZUKA, Tetsuro MIZUSHIMA, ...
2008 Volume 36 Issue APLS Pages
1046-1048
Published: 2008
Released on J-STAGE: December 25, 2008
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A compact, high power SHG green light source with wide operation temperature range over 30 degrees Celsius has been developed by using a wavelength-locked laser diode and a 0.5mm-long periodically poled Mg:LiNbO
3(PPMgLN). A continuous green light of 1.7W was generated by intracavity frequency doubling of a Nd:YVO
4 laser with the PPMgLN. The wall-plug efficiency was as high as 18.9%. The volume of the green light source was 2cc.
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Weili ZHANG, Guangqiang SHANG, Jianda SHAO, Zhengxiu FAN
2008 Volume 36 Issue APLS Pages
1049-1052
Published: 2008
Released on J-STAGE: December 25, 2008
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The properties of third harmonic beam splitters for high power laser system were studied in this paper. The third harmonic beam splitter, which has high transmittance at 1053nm and 527nm, and high reflectance at 351nm, was designed using regular quarter-wavelength stacks. Considering the optical properties, electric field distributions and experimental results, we concluded the film stack of Glass/(HL)
12 3H2M2L/Air) was a better option for obtaining a third harmonic beam splitter with high laser induced damage threshold (LIDT). In this study, electron beam evaporation was employed to fabricate these beam splitters on fused silica substrates. The experimental results showed that the samples had good optical performance. The LIDT at 355nm is about 10J/cm
2 (355nm, 7ns). To understand the influence of post-treatment on the LIDT of the beam splitter, the as-deposited coatings were treated in vacuum chamber with oxygen plasma and annealed in clean ambient air, respectively. The result exhibited the LIDT at 355nm was increased with oxygen plasma treatment, while decreased after annealing in clean ambient air.
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Qingwei YANG, Ailin GUO, Xinglong XIE, Fuling ZHANG, Meizhi SUN, Qi GA ...
2008 Volume 36 Issue APLS Pages
1053-1055
Published: 2008
Released on J-STAGE: December 25, 2008
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To ensure high contrast ratio for the SHENGUANG (SG) II petawatt upgrade laser facility, many factors such as pulse spectral clipping, chromatic aberration and manufacture errors of the optical elements are considered carefully in the design of the pulse stretcher. An eight pass Öffner configuration is selected for the laser system and the final design of the stretcher is also given out.
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Junji KAWANAKA, Koichi YAMAKAWA, Koji TSUBAKIMOTO, Tadashi KANABE, Tos ...
2008 Volume 36 Issue APLS Pages
1056-1058
Published: 2008
Released on J-STAGE: December 25, 2008
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A new diode-pumped laser fusion driver has been conceptually designed at 16-Hz repetition rate, 17% electrical-optical efficiency and less than 3000-m
3 main amplifier size. Output power is 1.2 MJ for a blue compression laser and 0.1 MJ for a heating laser. 1-kJ pulse energy in near infrared is a basic unit to obtain such megajoules energy. We have proposed two new technologies into the system. One is cryogenic Yb:YAG ceramics as a laser material. The other is a large-aperture active-mirror as amplifier architecture. Recently, 1-kJ laser system "GENBU" has been designed in details with these technologies as a milestone for the new driver. A 1-J system "GENBU-Kid" is under construction for power-scaling up to 1 kJ.
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Ryo YASUHARA, Takashi SEKINE, Takashi KURITA, Tadashi IKEGAWA, Osamu M ...
2008 Volume 36 Issue APLS Pages
1059-1061
Published: 2008
Released on J-STAGE: December 25, 2008
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We report a high average power and high pulse energy diode-pumped Nd:glass master oscillator power amplifier system that is consisted of a thermally-edge-controlled zigzag slab amplifier and stimulated Brillouin scattering (SBS) mirror for use of pumping source of ultra intense laser system. This phase conjugated system produces an average power of 213 W at 10 Hz in 8.9-ns pulse (2.4 GW peak power) with an optical-to-optical conversion efficiency of 11.7 % and a near diffraction limited beam quality. To the best of our knowledge these results represent the highest average power achieved from a Nd:glass based laser amplifier system.
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Yong-Zhen HUANG, Yong-Hong HU, Shi-Jiang WANG, Yue-De YANG, Wei ZHAO
2008 Volume 36 Issue APLS Pages
1062-1065
Published: 2008
Released on J-STAGE: December 25, 2008
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Semiconductor microcavity lasers with directional emission are important for real applications. Different from the whispering-gallery modes (WGMs) in microdisk, the confined WGMs in triangle and square micro-resonators connected with an output waveguide can still have high Q-factors in some cases. Room temperature continue-wave electrically injected InGaAsP/InP equilateral-triangle-resonator lasers with the side length 10 to 30 µm are fabricated by standard photolithography, inductively coupled plasma (ICP) etching technique combined with wet chemical etching process. The lasers characteristics are measured and analyzed over temperature range 80-300 K. The influences of the output waveguide on the mode Q-factor and the output coupling efficiency for square micro-resonators are numerically simulated by the finite-difference time-domain (FDTD) techniques. In addition, mode coupling between the WGMs and vertical radiation modes in the cladding layer are investigated by 3D FDTD technique for microcavities with vertical semiconductor confinement.
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Tomohiro IMAHOKO, Norihiro INOUE, Kazuya TAKASAGO, Masanao KAMATA, Tet ...
2008 Volume 36 Issue APLS Pages
1066-1068
Published: 2008
Released on J-STAGE: December 25, 2008
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We have developed a cryogenically cooled Ti:sapphire regenerative amplifier at the repetition rate of up to 100 kHz which was pumped by the intracavity SHG pulses of Yb:YAG thin disk laser. An electro-optic (EO) switching device employing a β-barium borate (β-BBO) crystal was used for pulse extraction from the amplifier resonator. The maximum average amplified power obtained was 21 W under the two pumping pump powers of 70 W at 50 kHz and 75 W at 100 kHz. The amplified pulse was able to be compressed to 200 fs by a grating pair compressor, and the output power was 12.4 W at 50 kHz. The cryogenic cooling system made Ti:sapphire crystal capable to be pumped with over 70 W SHG power in order to keep the stable condition of the regenerative amplifier resonator.
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Yinghong XUE, Sadao UEMURA, Kenji TORIZUKA
2008 Volume 36 Issue APLS Pages
1069-1072
Published: 2008
Released on J-STAGE: December 25, 2008
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We have demonstrated and analyzed a high-power continuous-wave (cw) Yb:YAG laser directly pumped into the upper lasing level by a fiber-coupled laser diode with a center wavelength of 969 nm. The output power and the beam quality were compared by changing the laser-medium length and the focal length of pump-focusing lens. From a cw Yb:YAG laser with a 5-mm-long crystal and a pump-focusing lens with a focal length of 60 mm, an output power of 18.1 W has been obtained at center wavelength of 1031 nm. The M
2 factors of the laser beam are 1.71 in the horizontal direction and 1.47 in the vertical direction.
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Shinki NAKAMURA, Hiroaki YOSHIOKA, Yu MATSUBARA, Takayo OGAWA, Satoshi ...
2008 Volume 36 Issue APLS Pages
1073-1076
Published: 2008
Released on J-STAGE: December 25, 2008
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A high-power efficient ceramic Yb:YAG laser was demonstrated at a room temperature of 20°C with an Yb concentration of 9.8 at.%, a gain medium of 1 mm, a pumping power of 13.8 W, an output coupler of
T = 10%, and a cavity length of 20 mm. A 6.8 W cw output power was obtained with a slope efficiency of 72%. The ceramic Yb:YAG laser exhibited a continuous tunability in the spectral range of 63.5 nm from 1020.1 to 1083.6 nm for
T = 1% at a maximum output power of 1.6 W. To the best of our knowledge, this is the first study of the tunability of ceramic Yb:YAG lasers, except crystal Yb:YAG studies.
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Hongjun LIU, Cunxiao GAO, Jintao TAO, Wei ZHAO, Yishan WANG, Guofu CHE ...
2008 Volume 36 Issue APLS Pages
1077-1080
Published: 2008
Released on J-STAGE: December 25, 2008
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A fiber tunable high-power picosecond laser system has been for the first time demonstrated. A gain switch semiconductor laser diode was introduced as seed source, and a multi-stage single mode Yb-doped fiber amplifier was combined with a single mode double-clad Yb-doped fiber amplifier to construct the amplification system. High stability and good beam quality pulses with 1MHz tunable repetition rate, 3W average power, 90ps pulse duration, and central wavelength tunable from 1053 nm to 1073 nm were generated. The completely fiber integrated approach has the potential to be scaled to significantly higher average powers.
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Yoichi SATO, Hideki ISHIZUKI, Takunori TAIRA
2008 Volume 36 Issue APLS Pages
1081-1084
Published: 2008
Released on J-STAGE: December 25, 2008
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We have proposed a novel model of thermal conductivity in various optical materials. This numerical model for thermal conductivity requires one material parameter for isovolumic specific heat and two parameters for thermal diffusivity in the calculation of each optical material. The validity of our model was demonstrated and it was adequately able to present thermal conductivities between 25°C and 200°C in Y
3Al
5O
12, YVO
4, GdVO
4, stoichiometric and congruent LiTaO
3, and synthetic quartz.
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Friedrich BACHMANN
2008 Volume 36 Issue APLS Pages
1085-1088
Published: 2008
Released on J-STAGE: December 25, 2008
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High power diode lasers become more and more important, not only as a pumping source for disc and fiber type solid state lasers, but also in direct use e.g. for materials processing, for medical applications and for display technology. Against the background of all these applications increase of brilliance, i.e. enhancement of power and improvement of beam quality and for technical and economic reasons at the same time extension of lifetime and raise of power conversion efficiency are the major goals in activities in research facilities all over the world. Re¬cognizing the importance of optical technologies in general for the German economy a special funding program "Optical Technologies - made in Germany" has been launched by the German Federal Ministry of Education and Research (BMBF) in 2002. In frame of this program technology and applications of diode lasers are intensively studied in the BRIOLAS-initiative.
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Jun IZAWA, Fumio MATSUZAKA, Kenichirou NISHIDA, Ryuusuke KAWAKAMI, Nor ...
2008 Volume 36 Issue APLS Pages
1089-1091
Published: 2008
Released on J-STAGE: December 25, 2008
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Recently, we have demonstrated high average-power SHG generation by LD-pumped kHz-class pulsed Nd:YAG laser. Using this technique, we have developed a green laser for the YAG Laser Annealing System. We have obtained a green output with high average power (160W) and high pulse-energy (80mJ/pulse). By using an intra-cavity oscillator, a stability of laser beam and efficiency from pumping-LD to the green output are improved on a few times from our recent system with extra-cavity SHG method.
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Ryo YASUHARA, Ryuji KATAI, Junji KAWANAKA, Toshiyuki KAWASHIMA, Hirofu ...
2008 Volume 36 Issue APLS Pages
1092-1093
Published: 2008
Released on J-STAGE: December 25, 2008
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As the first step for GENBU main laser, we have designed a 1 J x 100 Hz nanosecond-pulsed average power laser system in order to demonstrate the advanced technologies such as cryogenic cooled Yb:YAG laser medium, active mirror geometry and scalability of this concept.
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Qinjun PENG, Xiaoyang WANG, Yong ZHOU, Yong ZHU, Chengming LI, Zhanggu ...
2008 Volume 36 Issue APLS Pages
1094-1097
Published: 2008
Released on J-STAGE: December 25, 2008
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General review for the progress on all solid state deep ultraviolet (DUV) laser with a KBe
2BO
3F
2 (KBBF) crystal was given in the paper. The frequency-conversion characteristics of KBBF crystal and the comparison between this crystal and other borate nonlinear optical crystals were simply described. A special prism coupling technique (PCT) for DUV laser generation and some excellent experimental results from the application of this crystal were commented. At last, we believe that the output power and conversion efficiency could be greatly increased in the future if the thicker KBBF crystal with good optical quality is grown and the application technique of solid state DUV laser is further developed.
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Naoomi MIYAKAWA, Nobuyoshi OHTANI, Toshihiko ADARI, Shigeru YAMAGUCHI, ...
2008 Volume 36 Issue APLS Pages
1098-1101
Published: 2008
Released on J-STAGE: December 25, 2008
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A resonator using w-axicon and axicon mirrors for a double coaxial electrode discharge CO
2 laser is analyzed using the vector field, iterative reflection method. A uniform ring-shaped output mode is expected even with struts in the electrode in the multi kW scheme.
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Abdolreza AMANI EILANLOU, Yasuo NABEKAWA, Kenichi L. ISHIKAWA, Hiroyuk ...
2008 Volume 36 Issue APLS Pages
1102-1104
Published: 2008
Released on J-STAGE: December 25, 2008
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We have developed an amplifier chain of Ti:Sapphire laser with a spectral width of more than 200 nm, which potentially generates a terawatt sub-10 fs pulse. This laser system consists of a Ti:Sapphire oscillator followed by a pulse stretcher, dispersion compensator with an SLM and the amplifier chain. The first amplifier is a regenerative one pumped by a green laser with energy of 11.5 mJ at 1 kHz. We could successfully compensate for the gain narrowing during regenerative amplification by using high-damage-threshold chirped mirrors and specially designed partial mirrors in the cavity, resulting in pulse energy of 73 µJ. The output pulse is sent to a beam-slicer to reduce the repetition rate to 10 Hz. After 5-pass amplification in a multi-pass amplifier pumped by the second harmonic of a YAG laser with an energy of 180 mJ, we obtained an amplified pulse energy of 30 mJ.
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Chunmei ZHANG, Jianliang WANG, Chuang LI, Xiaowei CHEN, Yuxin LENG, Li ...
2008 Volume 36 Issue APLS Pages
1105-1108
Published: 2008
Released on J-STAGE: December 25, 2008
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The intensity-dependent nonlinear ellipse rotation of high-energy femtosecond pulse in BK7 glass plate is researched experimentally. The polarization, spectrum and shape of the femtosecond pulse were studied in this process. Based on this scheme, we develop a pulse temporal cleaner, which has been used in our femtosecond chirped pulse amplification (CPA) laser to provide a contrast ratio improvement of 2 orders of magnitude for the milli-joule level fs input pulses. The total transmission efficiency of the cleaner reaches 16.7%.
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Takuya KANAI, Samuel BOHMAN, Akira SUDA, Shigeru YAMAGUCHI, Katsumi MI ...
2008 Volume 36 Issue APLS Pages
1109-1112
Published: 2008
Released on J-STAGE: December 25, 2008
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We have developed and demonstrated a pointing and power stabilization system for intense few-cycle pulse generation at high repetition rates. The output power from a 1 kHz Ti:sapphire laser system was controlled by the voltage applied to a Pockels cell, and the beam pointing was controlled by a fast analog device composed of a position-sensitive detector and a piezo-driven mirror. As a result, the pointing and power fluctuations were stabilized within 1 µm rms and 0.15% rms, respectively, by feedback control. After spectral broadening inside a hollow fiber for pulse compression, the fluctuations in the output power and spectral intensity were 1.1% rms and 3.5% rms, respectively. Finally, we obtained stable intense few-cycle pulses with an energy of 2.7 mJ and a pulse duration of 5.4 fs.
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Hajime NISHIOKA, Shuji OHTA, Hitoshi TOMITA
2008 Volume 36 Issue APLS Pages
1113-1115
Published: 2008
Released on J-STAGE: December 25, 2008
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Few-cycle pulse amplification by two-photon arranged photorefractive device has been demonstrated. An extraction efficiency of 27 % has been achieved with a gain-bandwidth of 32 THz.
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Nam Seong KIM
2008 Volume 36 Issue APLS Pages
1115-1118
Published: 2008
Released on J-STAGE: December 25, 2008
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High-power pulse fiber lasers (HPPFLs) using Yb-doped double-clad fiber for industrial applications are evolved as two types including Seed LD-based Master-Oscillator Power-Amplifier (Seed-LD-MOPA) and Q-switched fiber-laser-based Master-Oscillator Power-Amplifier (QS-MOPA). Seed-LD-MOPA can change pulse duration and temporal pulse shape easily, but bad effects such as super-pulsing phenomena and Stimulated-Brillouin Scattering (SBS) should be suppressed which may damage the lasers or lower the average power. QS-MOPA has good power scalability, but the pulse duration and temporal pulse shape are not easily changed. These HPPFLs are penetrating into mass-production area of microelectronics industries such as semiconductor, display, and PCB industries. The microelectronics industry has market size of $390B in 2006 which compositions are $260B, $80B, and $50B for semiconductor, display, and PCB industries, respectively. In this review paper, the recent technology development of the pulse fiber lasers and their composing components, their industrial microelectronics applications, total microelectronics industry markets will be reviewed.
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Parshotam GUPTA, Prasad NAIK
2008 Volume 36 Issue APLS Pages
1119-1122
Published: 2008
Released on J-STAGE: December 25, 2008
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The Laser Plasma Division at the Raja Ramanna Centre for Advanced Technology (RRCAT), Indore has been engaged in research and development activities on laser plasma interaction using 10 TW, 45 fs, Ti:sapphire laser and a variety of in-house developed diagnostic systems for ultrashort laser pulses, plasma and x-ray radiation. Our recent studies include laser wakefield electron acceleration, high order harmonic generation, resonance enhancement of single harmonics, MeV energy bremsstrahlung radiation, absorption of ultrashort laser pulses in
in-situ produced metal clusters, and ultrashort pulse K-shell x-ray line emission. This paper briefly describes these studies and important results obtained.
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Hiroyuki DAIDO, Akifumi YOGO, Akito SAGISAKA, Koichi OGURA, Satoshi OR ...
2008 Volume 36 Issue APLS Pages
1123-1124
Published: 2008
Released on J-STAGE: December 25, 2008
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We are investigating the laser driven charged particle acceleration to develop a particle accelerator using an intense lasers with a focused intensity of >>10
18 W/cm
2. To monitor proton energy spectra as well as plasma parameters under the repetitive operation, we are using real time detectors. The proton energy of ~MeV is stably obtained for applications.
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Hiroaki NISHIMURA, Shinsuke FUJIOKA, Masashi SHIMOMURA, Hirokazu SAKAG ...
2008 Volume 36 Issue APLS Pages
1125-1128
Published: 2008
Released on J-STAGE: December 25, 2008
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Extreme ultraviolet (EUV) radiation from laser-produced plasma has been studied for mass-production of the next generation semiconductor devices with EUV lithography. A full set of experimental databases are provided for a wide range of parameters of lasers and targets. These data are utilized directly as a technical guide-line for EUV source system design in the industry as well as used to benchmark the radiation hydrodynamic code, including equation-of-state solvers and advanced atomic kinetic models, dedicated for EUV plasma predictions. Present status of the LPP EUV source studies is presented.
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Daisuke NAKAMURA, Koji TAMARU, Tomoya AKIYAMA, Tomohiro KAWANO, Akihik ...
2008 Volume 36 Issue APLS Pages
1129-1131
Published: 2008
Released on J-STAGE: December 25, 2008
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In the development of extreme ultraviolet (EUV) light source for EUV lithography systems by laser-produced plasma (LPP), mass-limited targets such as a micro-droplet were considered as promising targets for debris mitigation. In our study, the dynamics of debris from the tin (Sn) droplet target was investigated in order to establish the guideline for the optimum design of the mitigation system. The Sn micro-droplet targets used in the experiment were made with a help of pulsed-laser. The behaviors of the Sn atoms from the droplet target irradiated by the Nd:YAG laser were investigated using the laser-induced fluorescence (LIF) imaging method. Sn atoms were observed even from a small amount target such as several ten µm droplets, indicating the droplet of this size was not ionized completely by the single pulse of Nd:YAG laser. Furthermore, the ablation dynamics of the irradiated droplet was observed by a high-speed time-resolved imaging camera simultaneously with the LIF imaging.
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Akira SASAKI, Atsushi SUNAHARA, Katsunobu NISHIHARA, Takeshi NISHIKAWA ...
2008 Volume 36 Issue APLS Pages
1132-1135
Published: 2008
Released on J-STAGE: December 25, 2008
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A study of the coefficient of radiative transfer of Sn plasmas for the extreme ultra-violet (EUV) light source is presented. The atomic data of near 10 times ionized Sn ions are calculated using the Hullac code, and the emissivity and opacity are calculated using a collisional radiative model, which is used in the radiation hydrodynamics code to calculate the emission spectrum and conversion efficicency. The accuracy of the coefficients of radiative transfer are improved by considering the detailed spectral structure of strong 4d-4f resonance lines, as well as including a large number satellite lines, along with correction of transition wavelength after comparison with spectroscopic measurement.
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Yoshihiro OCHI, Tetsuya KAWACHI, Noboru HASEGAWA, Keisuke NAGASHIMA, M ...
2008 Volume 36 Issue APLS Pages
1136-1138
Published: 2008
Released on J-STAGE: December 25, 2008
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New driver laser system for the 0.1-Hz x-ray laser is described. The driver laser is based on CPA laser with Nd:glass power amplifier. By using flash lamp pumped zigzag slab amplifier, energy extraction of > 10 J can be obtained at 0.1-Hz operation. Pulse duration of the laser light after pulse compression is 3.6 ps. These energy and duration satisfy a condition for x-ray laser generation.
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Anle LEI, Kazuo TANAKA, Ryosuke KODAMA, Ken ADUMI, Hideaki HABARA, Yon ...
2008 Volume 36 Issue APLS Pages
1139-1141
Published: 2008
Released on J-STAGE: December 25, 2008
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High intensity laser propagation in plasmas is one of the key issues in fast ignition scheme of laser fusion energy. We have investigated experimentally and computationally the laser propagation in dense plasmas. The experiment demonstrates plasma channel formation and indicates laser propagation through overdense plamsas with relativistic self-focusing. The channel direction coincides with the laser axis. Two and three-dimensional particle-in-cell simulation reproduces the plasma channel and reveals that the laser propagation is dependent on the laser focus position in plasmas.
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Koji SHINMI, Makoto MATSUI, Kimiya KOMURASAKI, Yoshihiro ARAKAWA
2008 Volume 36 Issue APLS Pages
1142-1145
Published: 2008
Released on J-STAGE: December 25, 2008
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A continuous wave laser driven wind tunnel has been developed to produce high enthalpy flows to simulate atmospheric reentry environment. As a result of preliminary operation tests, high enthalpy argon/oxygen flows were successfully generated with the input laser power of 800 W, the plenum pressure of 950 kPa and the plume diameter of 15 mm. Next, plume characteristics were diagnosed by laser absorption spectroscopy. Consequently, the radial distributions of the specific enthalpy were measured. It was found that the specific enthalpy of flow was around 4 MJ/kg at the radial position r < 3 mm.
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Zheng Lin CHEN, Min CHEN, Zhan JIN, G. Ravindra KUMAR, Motoaki NAKATSU ...
2008 Volume 36 Issue APLS Pages
1146-1149
Published: 2008
Released on J-STAGE: December 25, 2008
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Several plasma devices to control energetic electrons produced by ultra-intense lasers are studied. Cone targets guide the lasers and electrons, and enhance the generation of energetic electrons consequently. Plasma fibers confine and guide the energetic electrons, and lead an electron beam with very small spatial spread. Plasma lenses transport and collimate the energetic electrons into a very tiny spot. Grating plasmas give out Smith-Purcell radiations. The energy concentration brought by these energetic electrons in the methods of plasma photonics is improved more than 3 magnitudes compared to the simple plane targets, and new radiation source with tunable wavelength induced by energetic electrons is available.
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Xuemei LI, Baifei SHEN, Xiaomei ZHANG, Zhangying JIN, Fengchao WANG
2008 Volume 36 Issue APLS Pages
1150-1152
Published: 2008
Released on J-STAGE: December 25, 2008
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The density reconstruction for dense DT plasmas with high temperature has been studied. In the simulation of a plasma density diagnostics, the energy loss of fast protons going through the plasmas is crucial. The fast protons used for the diagnostics may be generated in the laser-plasma interaction and the number of the proton sources is four. If the original and final energies of protons are given, we can do the density reconstruction using simultaneous iterative reconstruction technique (SIRT) without knowing the noise level of the final energy. It turns out that the accuracy is better than that of the Tikhonov regularization method based on the deviation principle of Morozov's principle. In addition, the SIRT is suitable when the data is incomplete.
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Takayuki FUNATSU, Takashi YABE, Tomomasa OHKUBO, Sigeaki UCHIDA, Kunio ...
2008 Volume 36 Issue APLS Pages
1153-1156
Published: 2008
Released on J-STAGE: December 25, 2008
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A new type of solar pumped laser system that has features of high-efficiency and low cost due to the use of a Fresnel lens and a Cr codoped Nd:YAG ceramic laser medium is reported in this paper. Slope efficiencies of 7 to 9% have been achieved. The laser output of about 80 W was achieved with the combination of a 4-m
2 Fresnel lens and solar light chamber as a secondary power concentrator. The maximum output from a unit area of the Fresnel lens was 20 W/m
2, which is 2.8 times larger than the previous results with a mirror type concentrator.
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Yasutaka SAKURAI, Takashi YABE, Kazunari IKUTA, Yuji SATO, Shigeaki UC ...
2008 Volume 36 Issue APLS Pages
1157-1160
Published: 2008
Released on J-STAGE: December 25, 2008
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Basic characteristics of magunesium (Mg) reactions with water vapor have been investigated. The reaction can be used as a part of solar energy cycle that emits no green-house effects gases. The reactions produce heat and hydrogen that is mixed with oxygen and further generates water vapor and heat. The high temperature steam can be used to drive either internal or external combustion engines. Dynamics of the reactions has been investigated experimentally and compared to a simple model of Mg fuel pellet reaction with water vapor. Both experimental data and theoretical analysis found optimization of Mg and water mixing ratio for maximum momentum generation.
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Kazuyoku TEI, Kazuhiko HORIOKA, Shigeki MUTO, Daichi SUGIMOTO, Goro WA ...
2008 Volume 36 Issue APLS Pages
1161-1163
Published: 2008
Released on J-STAGE: December 25, 2008
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Nozzle banks for an ejector-chemical oxygen-iodine laser consisting of two-dimensional slit nozzles with a trip-jet mixing system were tested in the cold- and hot-flow operation regimes. Horizontal Pitot scan experiments demonstrated that the mixing ability of the trips is excellent. The Mach number of the mixed flow was approximately 3. The gain measurements were conducted, and the results of measurements revealed that the maximum gain was around 0.6%/cm. The gain cut-off length was more than 200mm. The lasing experiments were also conducted, and the power was about 3kW at the chemical efficiency of about 20%.
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Hong Jin KONG, Du Hyun BEAK, Jin Woo YOON, Jae Sung SHIN
2008 Volume 36 Issue APLS Pages
1164-1167
Published: 2008
Released on J-STAGE: December 25, 2008
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The phase control of the stimulate Brillouin scattering (SBS) wave by a standing wave is the most important technique for the realization of the beam combination laser system. In this work, a theoretical model has been developed for explaining the principle of the phase controlling. The phase fluctuation of the SBS wave has been numerically calculated using this theoretical model. Consequently, it predicts the phase of the SBS wave will be stabilized as the fluctuation of the pump energy decreases and the pump energy increases. Furthermore, the change of the relative phase difference between the SBS waves can be easily calculated by this model in the beam combination laser system.
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Xuechun LI, Wei FAN, Hui WEI, Haidong ZHU, Jiangfeng WANG, Jie XIE, Li ...
2008 Volume 36 Issue APLS Pages
1168-1171
Published: 2008
Released on J-STAGE: December 25, 2008
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This article describes the front-end system for the SG-II high power laser facility. The front-end of SG-II is based on amplitude waveguide modulator pulse shaping technology and short pulse laser trigger synchronization technology. A phase modulator is used to broaden the frequency spectrum to suppress SBS effect. And a wide spectrum Nd:glass regenerative amplifier pumped by LD is developed. In order to improve the fill factor of the output laser beam to acquire maximum energy of SG-II, the spatial shaping system is developed to control the intensity distribution.
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Guang XU, Tao WANG, Zhaoyang LI, Yaping DAI, Zunqi LIN, Yuan GU, Jianq ...
2008 Volume 36 Issue APLS Pages
1172-1175
Published: 2008
Released on J-STAGE: December 25, 2008
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With the upgrade program of SG-II laser facility, 1kJ PW laser system based on its Nd:glass ninth beam has been designed for the scientific research on high energy density physics, ICF, especially the fast ignition. In this paper the design overview is presented. According to the schedule, the installation of optics and mechanics will be finished by the middle of 2009, and the operation will start in half year later.
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