Surface crystallization and second-order optical non-linearity in Gd2O3-Bi2O3-B2O3 glasses

Some ternary Gd2O3-Bi2O3-B2O3 glasses are prepared, and crystallization behavior and second harmonic intensity are examined to develop new non-linear optical crystallized glasses. The glasses with Gd2O3 contents of 8-14 mol% have large densities of over 6 g/cm3 and large refractive indices of ∼1.9. Transparent surface crystallized glasses consisting of two kinds of crystalline phases with different morphologies, i.e. plate shape and needle shape crystals, are fabricated by heat-treatment at temperatures between glass transition and crystallization temperatures. From second harmonic generation microscope observations, micro-Raman scattering spectra and XRD analyses, plate shape crystals are determined to be non-linear optical GdxBi1−xBO3 and needle shape crystals are Bi3B5O12 having no second-order optical non-linearity. Since crystallized glasses consisting of GdxBi1−xBO3 crystals exhibit relatively strong SHGs, they have a high potential for application to light control devices.