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Journal Articles

Ion species/energy dependence of irradiation-induced lattice structure transformation and surface hardness of Ni$$_{3}$$Nb and Ni$$_{3}$$Ta intermetallic compounds

Kojima, Hiroshi*; Kaneno, Yasuyuki*; Ochi, Masaaki*; Semboshi, Satoshi*; Hori, Fuminobu*; Saito, Yuichi*; Ishikawa, Norito; Okamoto, Yoshihiro; Iwase, Akihiro*

Materials Transactions, 58(5), p.739 - 748, 2017/05

 Times Cited Count:5 Percentile:26.42(Materials Science, Multidisciplinary)

Bulk samples of Ni$$_{3}$$Nb and Ni$$_{3}$$Ta intermetallic compounds were irradiated with 16 MeV Au, 4.5 MeV Ni, 4.5 MeV Al, 200 MeV Xe and 1.0 MeV He ions, and the change in near-surface lattice structure was investigated by means of the grazing incidence X-ray diffraction (GIXD)and EXAFS. The Ni$$_{3}$$Nb and Ni$$_{3}$$Ta lattice structures transform from the ordered structures (orthorhombic and monoclinic structures for Ni$$_{3}$$Nb and Ni$$_{3}$$Ta, respectively) to the amorphous state by the Au, Ni, Al and Xe ion irradiations. Irrespective of such heavy ion species or energies, the lattice structure transformation to the amorphous state almost correlate with the density of energy deposited through elastic collisions.

Journal Articles

High-efficiency contact grating fabricated on the basis of a Fabry-Perot type resonator for terahertz wave generation

Yoshida, Fumiko; Nagashima, Keisuke; Tsubouchi, Masaaki; Ochi, Yoshihiro; Maruyama, Momoko; Sugiyama, Akira

Japanese Journal of Applied Physics, 55(1), p.012201_1 - 012201_5, 2016/01

 Times Cited Count:6 Percentile:29.47(Physics, Applied)

Journal Articles

Yb:YAG thin-disk chirped pulse amplification laser system for intense terahertz pulse generation

Ochi, Yoshihiro; Nagashima, Keisuke; Maruyama, Momoko; Tsubouchi, Masaaki; Yoshida, Fumiko; Kono, Nanase; Mori, Michiaki; Sugiyama, Akira

Optics Express (Internet), 23(11), p.15057 - 15064, 2015/06

 Times Cited Count:25 Percentile:78.83(Optics)

We have developed a 1 kHz repetition picosecond laser system dedicated for intense terahertz (THz) pulse generation. The system comprises a chirped pulse amplification laser equipped with a Yb:YAG thin-disk amplifier. At room temperature, the Yb:YAG thin-disk regenerative amplifier provides pulses having energy of over 10 mJ and spectral bandwidth of 1.2 nm. The pulse duration achieved after passage through a diffraction grating pair compressor was 1.3 ps. By employing this picosecond laser as a pump source, THz pulses having a peak frequency of 0.3 THz and 4 $$mu$$J of energy were generated by means of optical rectification in an Mg-doped LiNbO$$_{3}$$ crystal.

Journal Articles

Current status of the driver laser system for intense terahertz wave generation

Tanaka, Momoko; Ochi, Yoshihiro; Kosuge, Atsushi; Okada, Hajime; Mori, Michiaki; Kiriyama, Hiromitsu; Tsubouchi, Masaaki; Nagashima, Keisuke

JAEA-Conf 2014-001, p.32 - 33, 2014/09

We have constructed a high power kHz laser system using Yb:YAG thin-disk as a gain medium for a driver laser of THz wave generation. A 4-bounce regenerative amplifier is constructed and output energy up to 10 mJ is obtained. Using compressed pulse, we demonstrated THz wave generation with LiNbO$$_{3}$$ crystal.

Journal Articles

Contact grating device with Fabry-Perot resonator for effective terahertz light generation

Tsubouchi, Masaaki; Nagashima, Keisuke; Yoshida, Fumiko; Ochi, Yoshihiro; Maruyama, Momoko

Optics Letters, 39(18), p.5439 - 5442, 2014/09

 Times Cited Count:34 Percentile:86.29(Optics)

A novel design for a contact grating device with an incorporated Fabry-Perot resonator is proposed for high-power terahertz light (THz) generation. We deposited a multilayer consisting of Ta$$_{2}$$O$$_{5}$$ and Al$$_{2}$$O$$_{3}$$ on a magnesium-doped stoichiometric LiNbO$$_{3}$$ substrate and fabricated grating grooves on the outermost layer. The multilayer was designed such that conditions for a Fabry-Perot resonator were satisfied for light diffracted by the grating. Consequently, the fraction of light transmitted into the LiNbO$$_{3}$$ substrate, i.e., the diffraction efficiency, was enhanced by the resonator. The diffraction efficiency of the fabricated device was 71%, which is close to the calculated value of 78% from the optimized design. THz light generation was also demonstrated with the contact grating device. The THz output of 0.41 microJ was obtained using NIR pump light of 2.7 mJ.

Journal Articles

Nature of magnetic coupling between Mn ions in as-grown Ga$$_{1-x}$$Mn$$_{x}$$As studied by X-ray magnetic circular dichroism

Takeda, Yukiharu; Kobayashi, Masaki*; Okane, Tetsuo; Okochi, Takuo*; Okamoto, Jun*; Saito, Yuji; Kobayashi, Keisuke*; Yamagami, Hiroshi; Fujimori, Atsushi*; Tanaka, Arata*; et al.

Hoshako, 22(4), p.202 - 209, 2009/07

no abstracts in English

Journal Articles

Nature of magnetic coupling between Mn ions in as-grown Ga$$_{1-x}$$Mn$$_{x}$$As studied by X-ray magnetic circular dichroism

Takeda, Yukiharu; Kobayashi, Masaki*; Okane, Tetsuo; Okochi, Takuo; Okamoto, Jun*; Saito, Yuji; Kobayashi, Keisuke*; Yamagami, Hiroshi; Fujimori, Atsushi; Tanaka, Arata*; et al.

Physical Review Letters, 100(24), p.247202_1 - 247202_4, 2008/06

 Times Cited Count:39 Percentile:82.23(Physics, Multidisciplinary)

no abstracts in English

Oral presentation

Nature of magnetic coupling between Mn ions in as-grown Ga$$_{1-x}$$Mn$$_{x}$$As studied by X-ray magnetic circular dichroism

Takeda, Yukiharu; Kobayashi, Masaki*; Okane, Tetsuo; Okochi, Takuo; Okamoto, Jun*; Saito, Yuji; Kobayashi, Keisuke*; Yamagami, Hiroshi; Fujimori, Atsushi; Tanaka, Arata*; et al.

no journal, , 

no abstracts in English

Oral presentation

Annual progress and future plans of Laser R&D Group

Sugiyama, Akira; Kiriyama, Hiromitsu; Ochi, Yoshihiro; Tanaka, Momoko; Nakai, Yoshiki; Sasao, Hajime; Tateno, Ryo; Okada, Hajime; Kosuge, Atsushi; Tsubouchi, Masaaki

no journal, , 

The main subject of our group is upgrade of J-KAREN and TOPAZ laser systems. The J-KAREN achieves the potential for generating a peak power of 500 TW, and exceeds a contrast ratio of 10E10. The TOPAZ achieves pulse power of 15 J at a repetition rate of 0.1 Hz. We also started a development of another laser system named QUADRA (Quality Ultra ADvanced RAdiation Source) in C-Phost. The QUADRA system is a high averaged short pulse laser pumped by high power LD at kHz repetition rate. This development is essential for the developments of other new laser systems in the next 5-year program of JAEA.

Oral presentation

Development for intense THz light generation in KPSI

Tsubouchi, Masaaki; Ochi, Yoshihiro; Tanaka, Momoko; Yoshida, Fumiko; Nagashima, Keisuke

no journal, , 

In KPSI, we are developing the intense THz light generation apparatus. In this presentation, we will introduce the current status of the developing the apparatus, including the pump laser system, THz generation and detection system, and so on. The pulse shaping is also important for the practical use of the THz light. As the first step, we have developed the THz etalon with an optical shutter.

Oral presentation

Development of intense THz light source, 2; Generation of THz light

Tsubouchi, Masaaki; Ochi, Yoshihiro; Tanaka, Momoko; Yoshida, Fumiko; Nagashima, Keisuke

no journal, , 

We have developed high repetition (1 kHz) intense THz laser light source for the molecular axis control by non-linear interaction between intense THz light and molecules.

Oral presentation

Generation of high power THz light for control of molecular rotation

Tsubouchi, Masaaki; Ochi, Yoshihiro; Tanaka, Momoko; Yoshida, Fumiko; Nagashima, Keisuke

no journal, , 

We are developing intense THz light source to realize control of molecular axis orientation in space. From the theoretical studies by Hebling and co-workers, it has been known that the desirable excitation NIR pulse for the THz light generation process in the Mg-sLiNbO$$_{3}$$ crystal should have the pulse width of 400 fs - 1 ps, and the tilted pulse front by 63 degree. To generate such NIR light, the Yb:YAG based amplifier system is one of the good candidates. By using this system, we are trying to generate the intense THz light with the high repetition rate (1 kHz).

Oral presentation

Development of intense THz light source, 1; Driver laser system and probe pulse generation

Ochi, Yoshihiro; Tsubouchi, Masaaki; Tanaka, Momoko; Yoshida, Fumiko; Nagashima, Keisuke; Sugiyama, Akira

no journal, , 

We will present current status of a driver laser system for intense THz wave generation. The driver laser system, QUADRA-T, is a 1 kHz repetition CPA laser equipped with Yb:YAG thin disk amplifier. Current output power from a regenerative amplifier is about 10 W (10 mJ/pulse). Upgrade to 100W class power output using a multi-pass amplifier is the next plan.

Oral presentation

Development of intense THz laser light for control of molecules

Tsubouchi, Masaaki; Ochi, Yoshihiro; Tanaka, Momoko; Yoshida, Fumiko; Nagashima, Keisuke

no journal, , 

We are developing intense THz light source to realize control of molecular axis orientation in space. From the theoretical studies by Hebling and co-workers, it has been known that the desirable excitation NIR pulse for the THz light generation process in the Mg-sLiNbO$$_{3}$$ crystal should have the pulse width of 400 fs $$sim$$ 1 ps, and the tilted pulse front by 63 degree. To generate such NIR light, the Yb:YAG based amplifier system is one of the good candidates. By using this system, we are trying to generate the intense THz light with the high repetition rate (1 kHz).

Oral presentation

Development of intense THz light for control of molecules

Tsubouchi, Masaaki; Ochi, Yoshihiro; Maruyama, Momoko; Yoshida, Fumiko; Nagashima, Keisuke

no journal, , 

The nonlinear interaction between terahertz (THz) light and matter has recently been of interest for its availability to control molecular alignment in space. The pulse train of the intense THz light is one of the candidates to align the molecules efficiently and nondestructively. In this study, we have developed the experimental apparatus to generate the intense THz light. The THz etalon to generate the THz pulse train has been presented in our previous study.

Oral presentation

High average power laser from Yb:YAG thin-disk amplifiers and its applications

Ochi, Yoshihiro; Nagashima, Keisuke; Maruyama, Momoko; Tsubouchi, Masaaki; Yoshida, Fumiko; Sugiyama, Akira

no journal, , 

We are developing a high average power laser system using Yb:YAG thin-disk amplifiers. Currently picoseconds pulses with 10 mJ energy are delivered from the regenerative amplifier at repetition rate of 1 kHz. The pulse energy will increase up to 100 mJ by a Yb:YAG thin-disk multi-pass amplifier. The picosecond pulses have been used in several applications such as intense THz light wave generation, laser induced damage test, and so on. I will present details of the laser system and preliminary results of applications.

Oral presentation

Generation of high power THz light by contact grating method

Tsubouchi, Masaaki; Nagashima, Keisuke; Yoshida, Fumiko; Ochi, Yoshihiro; Maruyama, Momoko

no journal, , 

The nonlinear interaction between terahertz (THz) light and matter has recently been of interest for its availability to control molecular alignment in space. The pulse train of the intense THz light is one of the candidates to align the molecules efficiently and nondestructively. In this study, we have developed the experimental apparatus to generate the intense THz light. The THz etalon to generate the THz pulse train has been presented in our previous study

Oral presentation

Contact grating device with Fabry-Perot resonator for effective THz light generation

Tsubouchi, Masaaki; Nagashima, Keisuke; Yoshida, Fumiko; Ochi, Yoshihiro; Maruyama, Momoko

no journal, , 

A novel design for a contact grating device with an incorporated Fabry-Perot resonator is proposed for high-power terahertz light (THz) generation. We deposited a multilayer consisting of Ta$$_{2}$$O$$_{5}$$ and Al$$_{2}$$O$$_{3}$$ on a magnesium-doped stoichiometric LiNbO$$_{3}$$ substrate and fabricated grating grooves on the outermost layer. The multilayer was designed such that conditions for a Fabry-Perot resonator were satisfied for light diffracted by the grating. Consequently, the fraction of light transmitted into the LiNbO$$_{3}$$ substrate, i.e., the diffraction efficiency, was enhanced by the resonator. The diffraction efficiency of the fabricated device was 71%, which is close to the calculated value of 78% from the optimized design. THz light generation was also demonstrated with the contact grating device. The THz output of 0.41 uJ was obtained using NIR pump light of 2.7 mJ.

Oral presentation

Contact grating device with Fabry-Perot resonator for effective THz light generation

Tsubouchi, Masaaki; Nagashima, Keisuke; Yoshida, Fumiko; Ochi, Yoshihiro; Maruyama, Momoko

no journal, , 

A novel design for a contact grating device with an incorporated Fabry-Perot resonator is proposed for high-power terahertz light (THz) generation. We deposited a multilayer consisting of Ta$$_{2}$$O$$_{5}$$ and Al$$_{2}$$O$$_{3}$$ on a magnesium-doped stoichiometric LiNbO$$_{3}$$ substrate and fabricated grating grooves on the outermost layer. The multilayer was designed such that conditions for a Fabry-Perot resonator were satisfied for light diffracted by the grating. Consequently, the diffraction efficiency was enhanced by the resonator. The diffraction efficiency of the fabricated device was 71%. THz light generation was also demonstrated with the contact grating device.

Oral presentation

Contact grating device with Fabry-Perot resonator for effective THz light generation

Tsubouchi, Masaaki; Nagashima, Keisuke; Yoshida, Fumiko; Ochi, Yoshihiro; Maruyama, Momoko

no journal, , 

A novel design for a contact grating device with an incorporated Fabry-Perot resonator is proposed for high-power terahertz light (THz) generation. We deposited a multilayer consisting of Ta$$_{2}$$O$$_{5}$$ and Al$$_{2}$$O$$_{3}$$ on a magnesium-doped stoichiometric LiNbO$$_{3}$$ substrate and fabricated grating grooves on the outermost layer. The multilayer was designed such that conditions for a Fabry-Perot resonator were satisfied for light diffracted by the grating. Consequently, the fraction of light transmitted into the LiNbO$$_{3}$$ substrate, i.e., the diffraction efficiency, was enhanced by the resonator. The diffraction efficiency of the fabricated device was 71%, which is close to the calculated value of 78% from the optimized design. THz light generation was also demonstrated with the contact grating device. The THz output of 410 nJ was obtained using NIR pump light of 2.7 mJ.

33 (Records 1-20 displayed on this page)