Large second-order optical nonlinearity in Ge-doped silica glass

Abstract We report on crystallization and second- and third-order optical nonlinearities of a GeO2SiO2 glass poled with ArF laser irradiation. A large coefficient of the second-harmonic generation (SHG), d, is induced, which is accompanied by generation of crystallites in the glass. Even after the d-coefficient decays out, the crystallites and the third-order optical susceptibility, χ(3), are retained. The result suggests that origin of the large SHG induced in the glass is associated with the formation of space-charge field in large χ(3) area.