Correlating structure with stress-optic response in non-oxide glasses

The stress-induced birefringence, known as the stress-optic response, of glasses in the Ge-P-S and Ge-Sb-S families were measured and correlated with structure. Birefringence of the samples was measured as a function of stress load, using the Sénarmont method. In addition, density, index of refraction, and shear moduli were determined. It was found that the glass structure correlated well with the stress-optic response, through a combination of the bond lengths and coordination numbers, as found previously for oxides. However, the zero stress-optic threshold behavior and magnitude of the effect differ from oxides, and these features are explained based on bonding differences and the smaller shear moduli in sulfides.