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149 results on '"Miura, Kenta"'

11. Coupled-wave analysis of vector holograms: effects of modulation depth of anisotropic phase retardation

Author

Sasaki, Tomoyuki, Miura, Kenta, Hanaizumi, Osamu, Emoto, Akira, and Ono, Hiroshi

Subjects
Electromagnetic waves -- Research, Modulation (Electronics) -- Research, Electromagnetic radiation -- Research, Holography -- Research, Anisotropy -- Research, Vector spaces -- Research, Electric waves -- Research, Astronomy, Physics
Abstract

The diffraction properties of thick vector holograms were analyzed with the use of a simple coupled-wave theory. Two eigenpolarizations in the holograms were determined based on the dielectric perturbation, and diffraction efficiencies for the polarizations were calculated by applying the Kogelnik method. The results were compared with those simulated by the finite-difference time-domain method. As a result, it was demonstrated that the diffraction efficiencies calculated by the two methods are in good agreement for any incident polarization when the modulation depth of the anisotropic phase retardation is substantially smaller than the mean retardation. In addition, we confirmed that coupled-wave analysis provides reasonable accuracy for relatively large modulation in the case of Bragg incidence with eigenpolarization. OCIS codes: 050.7330, 090.1970.

Published
2010

12. Fabrication of Two-Dimensional Arrays of Fluorescent Centers in Single-Crystalline Diamond Using Particle Beam Writing

Author

Haruyama, Moriyoshi, Suda, Yoshinori, Kada, Wataru, Onoda, Shinobu, Ohshima, Takeshi, Miura, Kenta, and Hanaizumi, Osamu

Abstract

Micrometer-scale patterning was performed using the particle beam writing technique with a focused heavy-ion microbeam, allowing the creation of a unique two-dimensional distribution of fluorescent centers in single-crystalline diamond. The focused nitrogen microbeam was scanned over the target of single-crystalline diamond prepared by chemical vapor deposition to create nitrogen-vacancy (NV) centers at defined positions. Imaging using a custom-built confocal fluorescence microscopy system revealed that the desired NV distribution was generated in the target crystal with a spatial resolution similar to the beam resolution. A two-dimensional matrix barcode test pattern was successfully generated in a diamond substrate to demonstrate the encryption of information inside a solid-state target.

Published
2018

15. In-plane light propagation in Ta[subscript 2]O[subscript 5]/SiO[subscript 2] autocloned photonic crystals

Author

Sato, Takashi, Ohtera, Yasuo, Ishino, Naoto, Miura, Kenta, and Kawakami, Shojiro

Subjects
Photonics -- Research, Crystal lattices -- Research, Integrated optics -- Research, Resonators -- Research, Optical waveguides -- Research, Optical instruments industry -- Research, Optoelectronics industry -- Research, Optoelectronic devices -- Research, Optoelectronic device, Business, Computers, Electronics, Electronics and electrical industries
Abstract

Light propagation in autocloned 2-D Ta[subscript 2]O[subscript 5]/SiO[subscript 2]photonic crystals, along the in-plane direction, is investigated, both numerically and experimentally.

Published
2002

16. Ion-Beam-Induced Luminescence Analysis of β-SiAlON:Eu Scintillator under Focused Microbeam Irradiation

Author

Kumar Parajuli, Raj, Kada, Wataru, Kawabata, Shunsuke, Matsubara, Yoshinori, Sakai, Makoto, Miura, Kenta, Satoh, Takahiro, Koka, Masashi, Yamada, Naoto, Kamiya, Tomihiro, Hanaizumi, Osamu, and Sato, Takahiro

Abstract

The scintillation properties and radiation durability of β-SiAlON:Eu were evaluated under focused microbeam irradiation conditions using 3 MeV protons. In situ observation of scintillation from β-SiAlON:Eu was monitored using ion-beam-induced luminescence (IBIL) and compared with that from ZnS:Ag scintillators. A comparison of the spectra of IBIL from both scintillators shows that the intensity of IBIL was analogous at di erent peak wavelengths of 545 nm for β-SiAlON:Eu and 450 nm for ZnS:Ag under the same irradiation conditions. Better radiation hardness towards focused proton microbeam irradiation was observed for the β-SiAlON:Eu scintillator when continuous measurements by IBIL were used. A decay constant of approximately 1.11 × 1016, which is two orders of magnitude higher than that for ZnS:Ag, was obtained for the β-SiAlON:Eu scintillator for focused proton microbeam irradiation. IBIL was also capable of visualizing a previously damaged area of a ZnS:Ag scintillator, which corresponds to the focused beam scanning area of 100 × 100 μm2. Meanwhile, the irradiated region was not signi cantly distinguishable from the nonirradiated region on the β-SiAlON:Eu scintillator under the same beam uence. These results suggest that β-SiAlON:Eu could be an ideal candidate scintillator for convenient ionized particle beam monitoring and a diagnostic tool for focused and intense beam uence conditions up to 10^16 ions/cm2.

Published
2016

24. Fabrication and evaluation of flexible Mach–Zehnder waveguide structure embedded in a poly(dimethylsiloxane) thin film using a proton microbeam

Author

Parajuli, Raj Kumar, primary, Saruya, Ryota, additional, Akutzu, Naoki, additional, Miura, Satoshi, additional, Kada, Wataru, additional, Kawabata, Shunsuke, additional, Matsubara, Yoshinori, additional, Satoh, Takahiro, additional, Koka, Masashi, additional, Yamada, Naoto, additional, Kamiya, Tomihiro, additional, Miura, Kenta, additional, and Hanaizumi, Osamu, additional

Published
2016
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25. Fabrication and evaluation of flexible Mach–Zehnder waveguide structure embedded in a poly(dimethylsiloxane) thin film using a proton microbeam

Author

Kumar, Parajuli Raj, Saruya, Ryota, Akutzu, Naoki, Miura, Satoshi, Kada, Wataru, Kawabata, Shunsuke, Matsubara, Yoshinori, Satoh, Takahiro, Koka, Masashi, Yamada, Naoto, Kamiya, Tomihiro, Miura, Kenta, and Hanaizumi, Osamu

Abstract

Micrometer-scale responses of radio-photoluminescence (RPL) glass dosimeters to focused ionized particle radiation were evaluated by combining ion-beam-induced luminescence (IBIL) and proton beam writing (PBW) using a 3MeV focused proton microbeam. RPL phosphate glass dosimeters doped with ionic Ag or Cu activators at concentrations of 0.2 and 0.1% were fabricated, and their scintillation intensities were evaluated by IBIL spectroscopy under a PBW micropatterning condition. Compared with the Ag-doped dosimeter, the Cu-doped dosimeter was more tolerant of the radiation, while the peak intensity of its luminescence was lower, under the precise dose control of the proton microprobe. Proton-irradiated areas were successfully recorded using these dosimeters and their RPL centers were visualized under 375 nm ultraviolet light. The reproduction of the irradiated region by post-RPL imaging suggests that precise estimation of irradiation dose using microdosimeters can be accomplished by optimizing RPL glass dosimeters for various proton microprobe applications in organic material analysis and in micrometer-scale material modifications.

Published
2016

47. Photoluminescence Properties of Yb and Ag Co-Doped Ta2O5 Thin Films

Author

Kanakubo, Masahiro, Miura, Kenta, Shimada, Keisuke, Fujii, Ryosuke, Noguchi, Katsuya, Kada, Wataru, and Hanaizumi, Osamu

Abstract

We prepared ytterbium and silver co-doped tantalum-oxide (Ta2O5:Yb,Ag) thin films using a simple co-sputtering method and evaluated photoluminescence (PL) properties of the films after annealing. We found that a PL peak at a wavelength of 980 nm due to Yb3+ can be strongly enhanced by Ag doping. From X-ray diffraction measurements, we found that Ag2Ta8O21 and orthorhombic Ta2O5 crystalline phases are very important in order to enhance the 980-nm peak observed from our Ta2O5:Yb,Ag thin films. Because of the human-body transmittability of the 980-nm wavelength, such films are applicable to a novel real-time X-ray dosimeter system.

Published
2018
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48. Demonstration of Thermo-Optic Switch Consisting of Mach-Zehnder Polymer Waveguide Drawn Using Focused Proton Beam

Author

Miura, Kenta, primary, Kiryu, Hiromu, additional, Ozawa, Yusuke, additional, Kubota, Atsushi, additional, Hiratani, Yuji, additional, Hanaizumi, Osamu, additional, Satoh, Takahiro, additional, Ishii, Yasuyuki, additional, Kohka, Masashi, additional, Takano, Katsuyoshi, additional, Ohkubo, Takeru, additional, Yamazaki, Akiyoshi, additional, Kada, Wataru, additional, Yokoyama, Akihito, additional, and Kamiya, Tomihiro, additional

Published
2013
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