Investigation of photo-activity of glasses 〜from the electronic and vibrational structures〜

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The purpose of the present study is the investigation of photo-activity of defects in glasses from view points of electronic and vibrational structures. The photo-chemistry of Ge-related defects and photorefractivity in Ge-doped silica glasses and development of the photo-active organic-inorganic hybrid materials were carried out.1. Photo-activity of Ge-related centers and enhanced photorefractivity in Ge-doped silica glassesThe most photo-active Ge-related center was found to be Ge^<2+> in silica glasses, which largely depends on the local structure of the Ge^<2+>-centers, whose activation energy of structural rearrangement responsible for photorefractive index change decreased with increasing the degree of freedom for the formation of illide structure (higher coordination structure). On the basis of the obtained results, highly photoactive Ge-doped silica glass thin film was deposited by CVD method, which exhibited >10^<-3> refractive index change by KrF excimer laser irradiation. Th … More e channel waveguides were directly written by laser irradiation. The waveguide Bragg grating was fabricated the direct writing technique.2. Micro-fabrication of organosiloxane containing photo-active substitutentsMicro-structures were fabricated in organosiloxane materials through photo-polymerization. The degree of polymerization of siloxane main chain and organic side group was independently controlled by the preparation conditions. Optical propoerties of the resultant materials were designed using the wide variety of material and fabrication parameters.3. Photo-thermal micro-fabrication of organic-inorganic hybrid materialsThe micro photonic structures were fabricated in the low-melting transparent hybrid materials through photo-thermal processes using heat generated by nonradiative phonon emission of excited ions or dyes. A very low power laser source less than several mW can be used for the micro fabrication because the materials to be fabricated exhibited low-melting point less than 200℃ Less