Crystallization and second-order optical nonlinearity in Ge-doped SiO₂ glass films

Abstract

It has been reported that a large second-order optical nonlinearity in Ge-doped SiO₂ glass induced by UV-poling is originated from crystallization and defect formation in UV-poled glass. To clarify the origin of crystallization in the glass system and apply it to the glass films, crystallization behavior in relation to defect conditions in Ge-doped SiO₂ glass films was investigated. We found that changing the lattice spacing is related to amount of GeO₂ in crystalline phase. We investigated crystallization caused by heat-treatment, and tried to obtain a new observation that heat-treating together with UV irradiation to samples.