Optical anisotropies in chalcogenide glasses induced by band-gap light

A model is proposed that qualitatively explains a variety of experiments on light-induced optical anisotropies in chalcogenide glasses and amorphous films. The model accounts for the sign of the observed anisotropies in thin films and predicts that even unpolarized light will cause these materials to become optically anisotropic. The model probably applies also to oxide glasses and other light-sensitive disordered materials and polymers. Photoinduced anisotropies are produced when one or both of the photocarriers excited by band-gap light remain in the absorbing microvolume and cause local changes in atomic bond configurations while recombining nonradiatively.