Details of a Researcher - Koike, Yasuhiro

Papers - Koike, Yasuhiro

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非複屈折性光学ポリマー固体

KOIKE YASUHIRO

Japanese Journal of Optics (Optical Society of Japan, (An Affiliate of The Japan Society of Applied Physics)) 第20 ( 第2 ) 80-81 1991.02

Research paper (scientific journal), Single Work

Contact Lens Prepared from Gradient Refractive Index Plastic Rod.PartⅢ;Application for Bifocal Contact Lens

KURIAKI MASAMITSU, NAKAMURA KANICHI, MIZUTANI YUTAKA, SAISIN MOTOTSUGU, UOZATO HIROSI, HARA YOSIAKI, OHTSUKA YASUJI, KOIKE YASUHIRO

Japanese Journal of Visual Science (日本眼光学会) Vol.11 ( No.1 ) 57-61 1990.10

Research paper (scientific journal), Joint Work

We have continued some works of the application of a GRIN plastic rod for a CL, the index is gradually increasing (a type of LDR, an application for (-) lens) and decreasing (a type of LFR, an application for (+) lens) to periphery of rod from principal optic axis. The report related to the application of GRIN-complexed LDR and LFR for bifocal CL. GRIN-complexed LFR in certain part and LDR in peripheral part was available to the bifocal of simultaneous type, arranging near zone in central part and distance zone in peripheral part. Also, GRIN-complexed LDR in central part and LFR in peripheral part was available to the bifocal CL of translating type, arranging distance zone in central part and near zone in peripheral part.

Graded-Index Optical Fibers of Methyl Methacrylate-Vinyl Benzoate Copolymer with Low Loss and High Bandwidth

OHTSUKA YASUJI, NIHEI EISUKE, KOIKE YASUHIRO

Applied Physics Letter Vol.57 ( No.2 ) 120-122 1990.08

Research paper (scientific journal), Joint Work, Accepted

The interfacial-gel copolymerization of 3/1, or 4/1 (wt/wt) MMA-VB monomer mixture followed by heat drawing result in GI POFs with attenuation loss of 212 and 134dB/km at 652nm, respectively, and with bandwidth of 170 and 260 MHz km, respectively, in comparison with 6 MHz km of the current SI POF. Now, it has been confirmed experimentally that GI fibers are tremendously superior to SI fibers for data-carrying capacity, while attenuation losses of both fibers are comparable.

Low-Loss GI Plastic Optical Fiber and Novel Optical Polymers

小池康博、二瓶栄輔、大塚保次

Specialty Polymer'90, Plenaly talk (Baltimore,USA) 1990.08

Joint Work

AT & T ベル研究所滞在レポートとプラスチック光ファイバの現状

KOIKE YASUHIRO

Optoelectronics Magazine New Era (日本鉱業株式会社) ( 7月 ) 36-39 1990.07

Research paper (scientific journal), Single Work

Graded-Index Plastic Optical Fiber Composed of Methyl Methacrylate and Vinyl Phenylacetate Copolymers

KOIKE YASUHIRO, NIHEI EISUKE, TANIO NORIHISA, OHTSUKA YASUJI

Applied Optics Vol.29 ( No.18 ) 2686-2691 1990.06

Research paper (scientific journal), Joint Work, Accepted

GI-POF whose transmission attenuation is 143dB/km at 651nm wavelength was fabricated by heat drawing the corresponding GI Preform rod. This rod is prepared by the interfacial-gel copolymerization technique of MMA and VPAc. The total scattering loss of the GI preform rod is 〜60dB/km at 633nm. The GI profiles of the optical fibers are almost the same as those of the corresponding preforms with cladding sheaths. The index distributions of their core regions are quadratic against the distance from the center axis. The numerical aperture estimated from the index is 〜0.20.

AT & T Bell Laboratories

KOIKE YASUHIRO

繊維と工業/繊維学会誌 (The Socety of Fiber Science and Technology) 第46 ( 1 ) 33-37 1990.01

Research paper (other academic), Single Work

Low-Loss GI Plastic Optical Fiber and Novel Optical Polymers

KOIKE YASUHIRO, OHTSUKA YASUJI

MRS Symposium Proceedings (Material Research Society (MRS)) Vol. 172 247-252 1990

Research paper (conference, symposium, etc.), Joint Work

Gradient-Index Polymer Materials and Their Optical Devices

KOIKE YASUHIRO, TANIO NORIHISA, NIHEI EISUKE, OHTSUKA YASUJI

Polymer Engineering and Science Vol.29 ( No.17 ) 1200-1204 1989.09

Research paper (scientific journal), Joint Work, Accepted

A GRIN plastic optical fiber was prepared by a heat drawing process of the GRIN preform rod obtained by a new interfacial-gel copolymerization technique. The attenuation loss of the GRIN fiber was 179kB/km at 650nm wave-length and its numerical aperture was 0.20-0.25. To attain low loss and highly dense integrated circuits, steric radial-GRIN optical waveguide components such as GRIN branching, star coupler, multi-coupler, and a 2-D GRIN lens array, were monolithically fabricated by this technique. A novel spherical GRIN sphere lens, whose index function is symmetrical about the center of the sphere, with a low spherical aberration, was prepared by a modified suspension polymerization technique. A W-shaped GRIN sphere has been newly proposed to further reduce the spherical aberration, compared with the parabolic GRIN sphere previously proposed.

Contact Lens Prepared from Gradient Refractive Index Rod. Part II; Application to (-) Lens of Light Diffusing Plastic Rod.

M. Kuriaki, J. Mizutani, Y. Mizutani, M. Saishin, H. Uozato, Y. Hara, Y. Ohtsuka, and Y. Koike

Japanese Journal of Visual Science (日本眼光学会) Vol.10 ( No.1 ) 40-45 1989.03

Research paper (scientific journal), Joint Work

Light Scattering and Heterogeneities in Low-Loss Poly(Methyl Methacrylate) Glasses

KOIKE YASUHIRO, TANIO NORIHISA, OHTSUKA YASUJI

Macromolecules, VOl.22 ( No. 3 ) 1367-1373 1989.03

Research paper (scientific journal), Joint Work, Accepted

A PMMA glass was prepared for the first time, in which the light-scattering loss was much smaller than any reported data and no large size of heterogeneities existed. The total scattering loss was much 13dB/km which represents an intrinsic limiting loss of the PMMA glasses attainable in the atmosphere. The isotropic scattering loss widely varied between ca. 9 and 400 dB/km according to the conditions of polymerization or heat treatment, while the anisotropic scattering loss was almost unchanged in the range 4-6 db/km. The origins of the large heterogeneities with the diameter of ca. 1000Å, which have been invariably observed in PMMA glasses reported so far, were investigated by the angular dependence of the light scattering. The large excess scattering is caused mainly by the isotropic strain inhomogeneities caused during polymerization and not by a small amount of remaining monomers or additives, the molecular weight of polymers, the stereoregularity due to the specific tacticity of PMMA, or cross-linking as a result of the gel effect.

Inherent Light Scattering Losses by Amorphous Optical Polymer Glasses

TANIO NORIHISA, KOIKE YASUHIRO, OHTSUKA YASUJI

Polymer Journal (The Society of Polymer Science, Japan) Vol.21 ( No.3 ) 259-266 1989.03

Research paper (scientific journal), Joint Work

Inherent light scattering losses by several methacrylic ester polymers were investigated. The intensities of polymerization scattering Vv from PMMA reported so far were in the order of 10-5 cm-1 even in a sample polymerized with rigorous purification, and had angular dependence in its Vv intensity, which implied the existence of large size heterogeneities of several hundred Å. In this paper, alkyl (ethyl and isobutyl) and fluoroalkyl (trifluoroethyl and trihydroperfluoropropyl) methacrylate glasses as well as PMMA, in which the Vv intensities were in the order of 10-6 cm-1 and no large size of heterogeneities were recognized, were prepared for the first time. Considering that our data are quite near the value predicted by the thermally induced fluctuation theory, and on the basis of our previous study, it is suggested that the thermally induced fluctuation theory, and on the basis of our previous study, it is suggested that the scattering data presented in this paper show an inherent limited loss for these methacrylic ester polymer glass in the atmosphere.

Gradient Refractive Index Plastic Rod(GRIN)as Contact Lens Diffusing Plastic Rod(LDR)as(-)Lens Material

KURIAKI MASAMITSU, NAKAMURA KANICHI, MIZUTANI YUTAKA, SAISIN MOTOTSUGU, UOZATO HIROSI, HARA YOSHIAKI, OHTUSKA YASUJI, KOIKE YASUHIRO

Jourmal of Japan Contact Lens Society Vol.31 ( No.2 ) 163-170 1989.03

Research paper (scientific journal), Joint Work

We reported the application of a GRIN plastic rod, a type of light focusing rod (LFR), a material of comparatively high central refractive index, the index gradually decreasing from principal optic axis (POA) to periphery. The LFR-GRIN possesses excellent properties for use as material for positive power contact leness (CL). This paper concerns negative power CL material application of GRIN type of light diffusing rod (LDR), whose POA index is lowest, the index gradually increasing from POA to periphery. As well LFR-GRIN and GRIN complexed LFR-LDR were used in negative power CLs. The result was that the center thickness of a CL made from LDR-GRIN is thinner than PMMA. From a theoretical focusing viewpoint, because the power differential between the center part of the CL and the periphery ranges from 1.00D to 3.00D.

Optical Waveguide

KOIKE YASUHIRO

繊維と工業/繊維学会誌 (The Society of Fiber Science and Technology, Japan) 第45 ( 2 ) 62-67 1989.02

Research paper (scientific journal), Single Work

Temparature Dependence of Light Scattering by Low-Loss Poly(Methyl Methacrylate) Glasses

TANIO NORIHISA, KOIKE YASUHIRO, OHTSUKA YASUJI

Polymer Journal (The Society of Polymer Science, Japan) Vol.21 ( No.2 ) 119-125 1989.02

Research paper (scientific journal), Joint Work, Accepted

A PMMA glass with the lowest light scattering loss among data reported so far and with no angular dependence in its scattering intensity was prepared by radical polymerization above Tg (Sample A). The temperature dependence of the light scattering intensity for this PMMA glass was investigated, in comparison with the PMMA glass polymerized below Tg and having excess scattering loss due to large-size heterogeneous structures (Sample B). In the sample A, the polarized scattering intensity (Vv) slightly changed below Tg and increased smoothly with increasing temperature above Tg in accordance with the fluctuation theory for structureless liquids. On the other hand, in the sample B, an abrupt decrease in Vv scattering around Tg was observed with increasing temperature. On the basis also of our previous study, it is suggested that the different trend of temperature dependence of light scattering and of excess scattering even in highly purified PMMA glasses depends on whether the strain inhomogeneities generated during the polymerization process are already relaxed above Tg or retained below Tg, and that the scattering behavior is not directly affected by first order structures such as molecular weight, tacticity, and remaining monomers.

Refractive Index, Refractive Index Distribution, Birefringence

KOIKE YASUHIRO

高分子/高分子学会誌 (The Society of Polymer Science, Japan) 37 ( 10月 ) 768-771 1988.10

Research paper (other academic), Single Work

High-Bandwidth, Low-Loss Graded-index Polymer Optical Fiber

石榑崇明、二瓶栄輔、小池康博

24^th^ European Conference on Optical Communication (ECOC'98), (Madrid,Spain),1988 1988.09

Joint Work

A Contact Lans Prepared from Gradient Index Material

YUUKI HIROTO, MIZUTANI JUN, MIZUTANI YUTAKA, OHTSUKA YASUJI KOIKE YASUHIRO

Japanese Joumal of Visual Science (日本眼光学会) Vol.9 ( No.1 ) 24-29 1988.05

Research paper (scientific journal), Joint Work

In this paper we report that plastic with GRIN was applied to material of contact lens. The plastic GRIN was successfully prepared by a special 2 step co-polymerization technique. The index profile of the plastic GRIN was measured by shearing interferometry. It was confirmed that the index profile was almost quadratic and the index difference between at the center and at the periphery was 0.03. We confirmed that the plastic GRIN corrects a spherical aberration of contact lens.

Gradient-Index Polymer Materials and Their Optical Devices

KOIKE YASUHIRO, OHTSUKA YAUJI

SPE-Society of Plastic Engineers 46^th^ Annual Technical Conference & Exhibits International Symposium of ANTIC'88 (SPE-Society of Plastic Engineers) 424-428 1988.04

Research paper (conference, symposium, etc.), Joint Work, Accepted

We have proposed four techniques to prepare axial-, radial-, spherical-, and other novelGRIN materials. The technologies of obtaining GRIN polymer and the resulting products, proposed in our laboratory until now are summerized. Since the two-step copolymerization and photocoplymerization techniques have been frequently reported so far, we focus, in this paper, on the GRIN optical fiber and optical waveguide by the interfacial-gel copolymerization technique, and the spherical GRIN spher lens with a low spherical aberration by the suspension polymerization technique.

New Interfacial-Gel Copolymerization Technique for Steric GRIN Polymer Optical Waveguides and Lens Arrays

KOIKE YASUHIRO, TAKEZAWA YOSHITAKA, OHTSUKA YASUJI

Applied Optics Vol.27 ( No.3 ) 486-491 1988.02

Research paper (scientific journal), Joint Work, Accepted

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