Opto-thermal instabilities in the optical parametric oscillator

Summary form only given. The self-pulsing behavior observed in the optical parametric oscillator cannot be described by the usual model involving only parametric interactions. In order to understand the origin of these instabilities, we have analysed the experimental data obtained from a nearly degenerate triply resonant optical parametric oscillator (OPO), pumped by a frequency-doubled YAG laser. The waveforms provide a clear signature of the influence of a slow variable on the dynamics. This can be the temperature, as is the case in our experiment, but other slow phenomena such as photoconduction could a priori lead to similar behaviors.