Laser-Induced Oscillatory Instabilities in Amorphous Materials

An oscillatory behaviour of the optical properties of amorphous materials is observed as a function of time, when the samples are irradiated by CW laser beams. The Raman TO peak and line width have a quasi-periodic behaviour parallel to that of the transmitted light, which indicate a structural oscillation between metastable states. A kinetic model is proposed, which is based on the generation of hot mobile electrons by the laser and on thermally activated atomic transitions between metastable states assisted by the transient local energy release caused by the electron trapping.