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Kishimoto, Maki; Namikawa, Kazumichi*; Sukegawa, Kota*; Yamatani, Hiroshi*; Hasegawa, Noboru; Tanaka, Momoko
Review of Scientific Instruments, 81(1), p.013905_1 - 013905_5, 2010/01
Times Cited Count：3 Percentile：17.89(Instruments & Instrumentation)We developed a new soft X-ray speckle intensity correlation spectroscopy system by use of a single shot high brilliant plasma soft X-ray laser. The plasma soft X-ray laser is characterized by several picoseconds in pulse width, more than 90% special coherence, and 10
soft X-ray photons within a single pulse. We developed a Michelson type delay pulse generator using a soft X-ray beam splitter to measure the intensity correlation of X-ray speckles from materials and succeeded in generating double coherent X-ray pulses with picosecond delay times. Moreover, we employed a high-speed soft X-ray streak camera for the picosecond time-resolved measurement of X-ray speckles. We performed the X-ray speckle intensity correlation measurements for probing the relaxation phenomena of polarizations in polarization clusters in the paraelectric phase of the ferroelectric material BaTiO
near its Curie temperature and verified its performance.
Nishikino, Masaharu; Ochi, Yoshihiro; Hasegawa, Noboru; Kawachi, Tetsuya; Yamatani, Hiroshi*; Oba, Toshiyuki; Kaihori, Takeshi; Nagashima, Keisuke
Review of Scientific Instruments, 80(1), p.116102_1 - 116102_3, 2009/11
Times Cited Count：15 Percentile：54.27(Instruments & Instrumentation)A highly coherent 13.9 nm X-ray laser is generated under an oscillator-amplifier configuration using a new tape target system and a driver laser system with a 0.1 Hz repetition rate. The output energy is comparable to the X-ray laser generated with a silver-deposited slab target, and the pointing stability using the new tape target system is better than conventional slab targets.
Hasegawa, Noboru; Kawachi, Tetsuya; Sasaki, Akira; Yamatani, Hiroshi; Kishimoto, Maki; Ochi, Yoshihiro; Tanaka, Momoko; Nishikino, Masaharu; Kunieda, Yuichi; Nagashima, Keisuke; et al.
Journal of Physics; Conference Series, 163(1), p.012062_1 - 012062_4, 2009/06
Times Cited Count：2 Percentile：66.39(Physics, Multidisciplinary)The precise knowledge about the wavelength and the spectral width of the lasing line is important for the applications of X-ray lasers, and especially for the spectral width, it is good benchmark of the atomic code because it depends on the electron collisional excitation and de-excitation rate coefficient. Only a few measurements of the spectral width of the laser line have been reported, because the spectral width of the X-ray laser is so narrow that the required spectral resolution is quite high. In this study, we took the nickel-like molybdenum X-ray laser as an example, and measure the spectral width by use of the high resolution spectrometer in order to compare it with a theoretical one.
Hasegawa, Noboru; Sasaki, Akira; Yamatani, Hiroshi; Kishimoto, Maki; Tanaka, Momoko; Ochi, Yoshihiro; Nishikino, Masaharu; Kunieda, Yuichi; Kawachi, Tetsuya; Yoneda, Hitoki*; et al.
Journal of the Optical Society of Korea, 13(1), p.60 - 64, 2009/03
Times Cited Count：5 Percentile：29.17(Optics)The precise knowledge about the spectral width of the X-ray laser line is important to generate the circularly polarized X-ray laser. There are three magnetic sub-levels at lower state of the collisional excitation X-ray laser transition of the nickel-like ion X-ray laser medium. The polarization of each transition is circular or linear. Therefore the circularly polarized X-ray laser could be extracted by the influence of the Zeeman effect if the X-ray laser medium was under the external magnetic field. The strength of the magnetic field required for the circularly polarized X-ray laser is determined by the spectral width of the X-ray laser. Only a few measurements of the spectral width of the laser line have been reported, because the spectral width of the X-ray laser is so narrow that the required spectral resolution is quite high. In this study, we took the nickel-like molybdenum X-ray laser as an example and succeeded the measurement of the spectral width of the X-ray laser.
Nakazato, Tomoharu*; Furukawa, Yusuke*; Tanaka, Momoko; Tatsumi, Toshihiro*; Nishikino, Masaharu; Yamatani, Hiroshi*; Nagashima, Keisuke; Kimura, Toyoaki*; Murakami, Hidetoshi*; Saito, Shigeki*; et al.
Journal of Crystal Growth, 311(3), p.875 - 877, 2009/01
Times Cited Count：25 Percentile：86.50(Crystallography)The temperature dependence of scintillation properties of a hydrothermal-method-grown zinc oxide (ZnO) emission is investigated using a nickel-like silver laser emitting at 13.9 nm. A broad peak at 386 nm with a full-width at half-maximum (FWHM) of 15 nm at room temperature (298 K) is obtained. The peak position tends to be blue shifted while the FWHM becomes narrower when the crystal temperature is decreased to 25 K. Streak images fitted by a double exponential decay reveal that the measured emission decay at 105 K was 
= 0.88 ns and 
= 2.7 ns. This decay time of a few nanoseconds is suitable for lithographic applications and is sufficiently short for the characterization of laser plasma extreme ultraviolet (EUV) sources with nanosecond durations.
Nishikino, Masaharu; Yamatani, Hiroshi; Nagashima, Keisuke; Kawachi, Tetsuya
X-Ray Lasers 2008; Springer Proceedings in Physics, Vol.130, p.427 - 432, 2009/00
The focused X-ray beam with a high intensity and a micron-order scale is expected to open various fields, such as the nonlinear phenomena, the nanoscale structuring of semiconductor material, and the X-ray probing of a single biological cell. A submicron soft X-ray beam is generated by a highly coherent soft X-ray laser at 13.9 nm with a Fresnel phase zone plate (FZP). The focused X-ray beam profile is measured using a knife-edge scan method. The submicron X-ray beam can also be used as the X-ray source of the Fourier transform holography. The FZP generates a point reference source and works as a beam splitter. The transmitted 0th order beam illuminates the object directly. A Fourier transform hologram is generated by the interference between the object wave diffracted from the object and the spherical reference wave. The holograms of the wire and the grid pattern are recorded with a CCD camera. The spatial resolution of the hologram will be presented.
Furukawa, Yusuke*; Tanaka, Momoko; Murakami, Hidetoshi*; Saito, Shigeki*; Sarukura, Nobuhiko*; Nishikino, Masaharu; Yamatani, Hiroshi; Nishimura, Hiroaki*; Mima, Kunioki*; Kagamitani, Yuji*; et al.
Reza Kenkyu, 36(APLS), p.1028 - 1030, 2008/12
Optical technologies in extreme ultraviolet (EUV) region have been receiving strong interests for the next generation lithography. Here we report properties of ZnO as scintillators in the EUV region, and to demonstrate the feasibility of using a Ni-like Ag EUV laser operated at 13.9-nm to evaluate these properties. The ZnO sample was irradiated with EUV laser pulses and the fluorescence was measured using a streak camera fitted with a spectrograph. A clear, excitonic, fluorescence peak was observed at around 380 nm with a decay lifetime of 3 ns. The prominent peak fluorescence is ideal for EUV detection and further applications including imaging.
Furukawa, Yusuke*; Tanaka, Momoko; Nakazato, Tomoharu*; Tatsumi, Toshihiro*; Nishikino, Masaharu; Yamatani, Hiroshi; Nagashima, Keisuke; Kimura, Toyoaki; Murakami, Hidetoshi*; Saito, Shigeki*; et al.
Journal of the Optical Society of America B, 25(7), p.B118 - B121, 2008/07
Times Cited Count：26 Percentile：74.28(Optics)Using EUV laser operated at 13.9 nm ZnO and GaN are shown to be excellent scintillators in this wavelength region. Especially ZnO has short response time of 3 ns and prominent peak fluorescence from excitation at 380 nm.
Nishikino, Masaharu; Hasegawa, Noboru; Kawachi, Tetsuya; Yamatani, Hiroshi; Sukegawa, Kota; Nagashima, Keisuke
Applied Optics, 47(8), p.1129 - 1134, 2008/03
Times Cited Count：43 Percentile：85.76(Optics)Tanaka, Momoko; Furukawa, Hiroyuki*; Murakami, Hidetoshi*; Saito, Shigeki*; Sarukura, Nobuhiko*; Nishikino, Masaharu; Yamatani, Hiroshi; Nagashima, Keisuke; Kagamitani, Yuji*; Ehrentraut, D.*; et al.
Journal of Physics; Conference Series, 112(4), p.042058_1 - 042058_4, 2008/00
Times Cited Count：1 Percentile：54.85(Physics, Fluids & Plasmas)Optical technologies in the extreme ultraviolet (EUV) region have been receiving strong interest for the next generation lithography. Efficient and fast scintillators are one of the key devices functioning in the EUV region. In this paper, we report excellent properties of ZnO and GaN as scintillators in the EUV region, and to demonstrate the feasibility of using a Ni-like Ag EUV laser operated at 13.9-nm to evaluate these properties. The sample was irradiated with EUV laser pulses, and the fluorescence spectrum and the fluorescence lifetime were measured using a streak camera fitted with a spectrograph. In the case of ZnO, a clear, excitonic, fluorescence peak was observed at around 380 nm with a decay lifetime of 3 ns. For GaN, a fluorescence peak at 370 nm having slower 5-ns decay time was observed. In this respect, the EUV scintillation properties of ZnO is said to be more favorable than GaN.
Tanaka, Momoko; Nishikino, Masaharu; Yamatani, Hiroshi; Nagashima, Keisuke; Kimura, Toyoaki; Furukawa, Yusuke*; Murakami, Hidetoshi*; Saito, Shigeki*; Sarukura, Nobuhiko*; Nishimura, Hiroaki*; et al.
Applied Physics Letters, 91(23), p.231117_1 - 231117_3, 2007/12
Times Cited Count：54 Percentile：84.95(Physics, Applied)The scintillation properties of a hydrothermal method grown zinc oxide (ZnO) crystal are evaluated for extreme ultraviolet (EUV) laser excitation at 13.9 nm wavelength. The exciton emission lifetime at around 380 nm is determined to be 1.1 ns, almost identical to ultraviolet laser excitation cases. This fast response time is sufficiently short for characterizing EUV lithography light sources having a few nanoseconds duration. The availability of large size ZnO crystal up to 3-inch is quite attractive for future lithography and imaging applications.
Ochi, Yoshihiro; Hasegawa, Noboru; Kawachi, Tetsuya; Nagashima, Keisuke; Kishimoto, Maki; Tanaka, Momoko; Nishikino, Masaharu; Sukegawa, Kota; Yamatani, Hiroshi; Kunieda, Yuichi; et al.
no journal, ,
We have developed a chirped pulse amplification laser with flash lamp pumped zigzag slab Nd:glass amplifiers for pumping the TCE X-ray lasers at 0.1-Hz repetition rate at the Japan Atomic Energy Agency. The laser provided 7 J/1.6 ps main pulse and 1/8 intensity pre-pulse at 1.2 ns before the main pulse. An energy fluctuation at 0.1-Hz operation was 20% (RMS), which was comparable with our present laser using rod amplifiers. The line focus on the target surface was 20 
m in the width and 0.8 cm in the length. By using this laser, gain saturated Ni-like silver laser (
= 13.9 nm) with energy output of 
1 J was obtained. The beam divergence of the Ni-like silver laser was 
mrad. Consequently, the peak spectrum brilliance was estimated to be 10
photons/s/mm
/mrad2/0.1%BW. With 0.1-Hz repetition rate, this X-ray laser can be a powerful tool for a variety of applications.
Ochi, Yoshihiro; Kishimoto, Maki; Hasegawa, Noboru; Kawachi, Tetsuya; Nagashima, Keisuke; Tanaka, Momoko; Nishikino, Masaharu; Kunieda, Yuichi; Yamatani, Hiroshi; Sukegawa, Kota
no journal, ,
no abstracts in English
Nishikino, Masaharu; Hasegawa, Noboru; Kawachi, Tetsuya; Ochi, Yoshihiro; Nagashima, Keisuke; Tanaka, Momoko; Kishimoto, Maki; Kunieda, Yuichi; Yamatani, Hiroshi
no journal, ,
We are developing plasma X-ray lasers pumped by ultra-short pulse lasers and have concentrated our efforts on developing a silver X-ray laser (13.9 nm) with spatially full coherence and application research using a highly coherent X-ray laser. Recently, we have developed a new pumping laser system, which is a CPA laser consisting of an OPCPA pre-amplifier and zigzag-slab type glass amplifiers. For the purpose of further application experiments, 0.1-Hz operation of the driver laser and the X-ray laser at a wavelength of 13.9 nm were succeeded.
Nakazato, Tomoharu*; Shimizu, Toshihiko*; Yamanoi, Kohei*; Sakai, Kohei*; Sarukura, Nobuhiko*; Ehrentraut, D.*; Fukuda, Tsuguo*; Tanaka, Momoko; Nishikino, Masaharu; Yamatani, Hiroshi*; et al.
no journal, ,
no abstracts in English
Nishikino, Masaharu; Yamatani, Hiroshi; Sukegawa, Kota; Nagashima, Keisuke
no journal, ,
no abstracts in English
Nishikino, Masaharu; Yamatani, Hiroshi; Sukegawa, Kota; Nagashima, Keisuke
no journal, ,
no abstracts in English
Furukawa, Yusuke*; Murakami, Hidetoshi*; Saito, Shigeki*; Sarukura, Nobuhiko*; Nishimura, Hiroaki*; Mima, Kunioki*; Tanaka, Momoko; Nishikino, Masaharu; Yamatani, Hiroshi; Nagashima, Keisuke; et al.
no journal, ,
Zinc oxide (ZnO) has previously been reported to be a potential light-emitting diode materia. We measured the time-resolved emission spectrum of a ZnO crystal for extreme ultraviolet (EUV) laser excitation at 13.9 nm wavelength and compared with UV excitation case. The emission lifetime was determined to be 2.6 ns. This value was not changed even for ultraviolet laser excitation. In the context of the nanosecond regime in the EUV region, ZnO crystal promises to be a feasible scintillation material.
Kawachi, Tetsuya; Nagashima, Keisuke; Kishimoto, Maki; Hasegawa, Noboru; Tanaka, Momoko; Ochi, Yoshihiro; Nishikino, Masaharu; Sukegawa, Kota; Yamatani, Hiroshi; Kunieda, Yuichi
no journal, ,
Laser-driven plasma X-ray laser is a promised compact, high quality X-ray source with high peak brilliance. Now using commercial base pumping laser, gain saturated X-ray laser has been obtained with the wavelength up to 12 nm with high repetition-rate. Furthermore using X-ray seeder and amplifier technique, we have demonstrated fully spatial coherent X-ray laser at a wavelength of 13.9 nm. In a view point of the application of X-ray lasers, using the coherence, high density plasma diagnostics by X-ray laser interferometer, surface investigation by X-ray speckle technique, and electron spectroscopy pumped by X-ray laser have been demonstrated, and the applicable research field is expanding with the increase of the repetition-rate. In this paper, the present status of the X-ray lasers and the future prospect will be presented including the applicable research fields and the possibility of shorter wavelength X-ray laser with KeV energy region.
Sarukura, Nobuhiko*; Furukawa, Yusuke*; Murakami, Hidetoshi*; Saito, Shigeki*; Nishimura, Hiroaki*; Mima, Kunioki*; Tanaka, Momoko; Nishikino, Masaharu; Yamatani, Hiroshi; Nagashima, Keisuke; et al.
no journal, ,
Optical technologies in the extreme ultraviolet (EUV) region have been receiving strong interest for the next generation lithography. Here we report properties of ZnO and GaN as scintillators in the EUV region, and to demonstrate the feasibility of using a Ni-like Ag EUV laser operated at 13.9-nm to evaluate these properties. The sample was irradiated with EUV laser pulses and the fluorescence were measured using a streak camera fitted with a spectrograph. In the case of ZnO, a clear, excitonic, fluorescence peak was observed at around 380 nm with a decay lifetime of 3 ns, as shown in Fig. 1. The prominent peak fluorescence is ideal for EUV detection and further applications including imaging. For GaN, a fluorescence peak at 370 nm having slower 5-ns decay time was observed. In this respect, the EUV scintillation properties of ZnO is said to be more favorable than GaN.
