| Co-Investigator(Kenkyū-buntansha) |
SAWADA Takeshi Nippon Telegraph and Telephone Corporation, Department of Engineering, Senior Engineer, 技術部・技術部門, 主査(研究職)
ANDO Isao Graduate School of Science & Technology, Tokyo Institute of Technology, Professor, 大学院・理工学研究科, 教授 (20016637)
KUROKI Shigeki Graduate School of Science & Technology, Tokyo Institute of Technology, Research Associate, 大学院・理工学研究科, 助手 (30293046)
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| Research Abstract |
Anisotropy in optical transmittance in the visible and near-infrared region was observed for uniaxially drawn and silver-dispersed polyimide films. The films were prepared in a one step operation, that is thermal curing and simultaneous uniaxial drawing of poly(amic acid)films dissolving 6〜25mol% of silver nitrate. The polyimide chains having a rod-like structure were oriented along the drawing direction during curing accompanying with the precipitation of silver nano-particles having elongated shapes. An anisotropy in transmittance of larger than 320 : 1(25dB)was obtained for a 14.8μm-thick film at 850nm with an transmittance of 80% perpendicular to the drawing direction, and its optical properties were retained after annealing at 150°C for 1h. This film suffices all the requirements for a thin-film polarizer inserted into a groove formed in silica-based waveguides. On the other hand, eight kinds of metal(Au, Ag, Pd, Cu, Al, Co, Fe, Ni)containing fluorinated polyimide films were prepared by thermal curing of poly(amic acid)s containing metallic salts or organo-metallic complexes. The chemical states, average sizes, and spatial distribution of the metallic particles were examined, and the thermal and optical properties of the films were compared with those of the host-polyimide. The precipitated metal particles increase the averaged refractive indices of the polyimides. All the films showed much less transparency in the visible region than the host-polyimide. However, the metal-containing films, except for the gold-containing film, showed transmittance higher than 80% in the near-infrared region(at 1550nm). Rotation of polarization of incident light was observed for a polyimide prepared from cobalt(hexafluoroacetylacetonate)by applying a magnetic field. This can be regarded as the optical Faraday effect caused by cobalt-containing nano-particles.
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