Akira J. Ikushima

Toyota Technological Institute

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Kazuya Saito

Osaka University

Hiroshi Kakiuchida

National Institute of Advanced Industrial Science and Technology

Takumi Fujiwara

Tohoku University

Kohji Ohbayashi

Nishogakusha University

Masaru Suzuki

Hokkaido University

Motoshi Ohama

Toyota Technological Institute

Masahide Takahashi

Osaka Metropolitan University

Fumitake Mimura

Kyushu Institute of Technology

Edson H. Sekiya

Toyota Technological Institute

Ichiro Hatta

Nagoya Industrial Science Research Institute

Cooperative Institutions

The University of Tokyo

Osaka University

Kyushu University

Hoya (Japan)

Nagoya University

Kyoto University

Toyota Technological Institute

Tohoku University

Institute for Solid State Physics and Optics

Tokyo University of Science

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Optical nonlinearities of a high concentration of small metal particles dispersed in glass: copper and silver particles

Journal of the Optical Society of America B (1994)

K. Uchida Shinji Kaneko S. Omi C. Hata Hiroaki Tanji

Third-order nonlinearities of glasses doped with a large number of copper or silver particles are studied by degenerate four-wave mixing with an emphasis on particle-size dependence. The nonlinear susceptibility χ(3) exhibits a peak at the wavelength of the absorption peak, with a maximum value of the order of 10−7 esu. The value of χ(3)/α is roughly independent of the absorption coefficient α and increases as the particle radius increases. This result is well explained by the size dependence of the imaginary part of the dielectric constant of metal particles and the local-field factor. The time response of the nonlinearity exhibits two-component behavior: the fast decay time is shorter than the pulse width of the laser (~12 ps), whereas the slow one is 120–200 ps, being weakly dependent on the radius.

10.1364/josab.11.001236

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Citations (374)

Decay behaviour of UV-induced defects in Ge-doped SiO/sub 2/ glass

Motoshi Ohama Takahiro Fujiwara Akira J. Ikushima

Decay behaviour of photo-induced defects in a Ge-doped SiO/sub 2/ glass with photosensitivity and 2nd-order optical nonlinearity has been presented. It has been found that the decay of induced GeE' in a UV-irradiated glass is quite different from that in a UV-poled glass.

Photosensitivity

10.1109/ecoc.1998.732474

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Poisson Lie Algebra Structures Associated with Three-Dimensional Lie Algebras

Fumitake Mimura Akira J. Ikushima

Graded Lie algebra

Source

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Energy levels of self-trapped holes in amorphous SiO₂: fictive temperature dependence

Journal of Physics D Applied Physics (2009)

Rongping Wang Kazuya Saito Akira J. Ikushima

Fictive temperature (Tf) dependence of self-trapped holes (STHs) in low temperature UV-irradiated silica glasses was systematically investigated by the electron spin resonance (ESR) method. The decay of the ESR signals was found to be bleaching photon energy dependent and to follow the stretched exponential decay function at each bleaching wavelength. When the one-photon process is dominant during the photo-bleaching process, where the recombination of electrons excited from the valence band with the holes in the STH band results in the decay of STH signals, the energy levels of STH1 were thus derived at 1.75 ± 0.02 eV, 1.61 ± 0.03 eV, 1.45 ± 0.05 eV and STH2 at 1.68 ± 0.02 eV, 1.44 ± 0.02 eV, 1.25 ± 0.04 eV, respectively, for Tf = 1500, 1350 and 1200 °C samples.

Photon energy

10.1088/0022-3727/42/9/095418

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Sound Attenuation and ³He–³He Interaction in ³He–⁴He Liquid Mixtures under Pressure

Japanese Journal of Applied Physics (1984)

Itsuhiro Fujii Akira J. Ikushima Masafumi Fukuhara Kazuyuki Kaneko

From sound attenuation measurements, 3 He– 3 He interaction potentials in 3 He– 4 He mixture under 10 and 20 bar have been determined. The measurements were carried out in mixtures of 3 He mole fraction ranging from 0.0289 to 0.0803. Superfluid transition temperatures of 3 He and other properties in the mixtures were then estimated from the deduced interaction potentials. The superfluid transition temperature for s-pairing was found to lower with increasing pressure, whereas a rather high transition temperature, as high as 100 µK, can be expected under 10 bar at the highest soluble 3 He concentration.

Helium-3

Bar (unit)

Isotopes of helium

10.7567/jjaps.23s1.57

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Silica-Based Glasses as Photonic Materials–Second-Order Nonlinearity Induced by UV-Poling–

Molecular crystals and liquid crystals science technology. Section A, Molecular crystals and liquid crystals/Molecular crystals and liquid crystals science and technology. Section A, Molecular crystals and liquid crystals (2000)

Akira J. Ikushima Takumi Fujiwara

Abstract After simultaneous applications of ultraviolet irradiation and a sufficiently high electric field, the so-called UV-poling, silica glass doped with germanium shows quite a large second-order optical nonlinearities in both bulk and film samples, and thus induced d coefficient is comparable to those of LiNbO3 crystal. The induced effect decays after the UV-poling with exactly a single exponential function of time, suggesting a kind of ordered structure formed in the glass by the UV-poling. The decay rate strongly indicates Ge-E′ centers to be relevant agents to the nonlinearity. The decay or degradation can be made much slower with addition of impurities as electron scavengers. Mechanism to give the nonlinearity will be discussed, relating to generation of crystallites in the glass.

Poling

Stretched exponential function

Exponential decay

Degradation

Ultraviolet

Silica glass

10.1080/10587250008025684

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Toward ultralucent optical fibers

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2001)

Akira J. Ikushima Kazuya Saito Hiroshi Kakiuchida

From infrared absorption spectra, the present authors elucidated behaviors of the structural relaxation in silica glass doped with various elements, and claim that sub-relaxation process exists besides the main-relaxation given by the viscous flow. Light scattering measurement also suggested the existence of such an additional relaxation channel. The sub- and main-structural relaxations are in general greatly accelerated by a proper dopant. And, the sub-relaxation, which extends below the glass transition temperature, gives a breakthrough to bring silica glass to a more stable structure even below the glass transition temperature. The sub-relaxation then reduces the Rayleigh scattering, a predominant component of the optical loss in the glass. Fluorine and chlorine seem to greatly accelerate the relaxations in silica glass.

Silica glass

Porous glass

Electret

10.1117/12.446557

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Thermal equilibrium of Ge-related defects in a GeO2-SiO2 glass

Applied Physics Letters (1998)

Masahide Takahashi Takumi Fujiwara Taiji Kawachi Akira J. Ikushima

In a 15.7 GeO2⋅84.3 SiO2 glass prepared by a vapor axial deposition method, optical absorptions at 4.92 and 5.08 eV were observed from 300 to 600 K. The results were then compared with electron spin resonance (ESR) measurement using the same samples. The absorption at 4.92 eV was found to increase with increasing temperature, while the optical absorption at 5.08 eV decreased with increasing temperature. These changes of optical absorption indicate that the concentration of neutral oxygen monovacancy is reduced at higher temperatures. The changes were quite reversible with the temperature. Concentration of Ge E′ center, estimated from ESR, increased with increasing temperature, which is in contrast with the decrease of neutral oxygen monovacancy. The present result strongly suggests the thermal equilibrium reaction between neutral oxygen monovacancy and Ge E′ center.

Thermal equilibrium

10.1063/1.121052

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Citations (16)

Improvement of the ultraviolet-proof property of silica glass fibers for ArF excimer-laser applications

Optics Letters (1999)

Kazuya Saito Akira J. Ikushima Takao Kotani Taisuke Miura

The effects of preirradiation by ArF excimer laser and thermal annealing on the transmission properties of a silica fiber were investigated. The durability of the fiber when it was exposed to ArF excimer laser irradiation was improved by preirradiation at room temperature and subsequent thermal annealing at 600 degrees C.

Ultraviolet

Excimer

Silica fiber

Silica glass

10.1364/ol.24.001678

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Citations (6)

Superconductivity in niobium and niobium-rich niobium-tantalum alloys

Physics Letters A (1968)

Akira J. Ikushima T. Mizusaki Tomoki Odaka

10.1016/0375-9601(68)90132-1

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Citations (13)