Self-pulsing instabilities in an optical parametric oscillator: Experimental observation and modeling of the mechanism

We have observed sustained self-pulsing in a continuously pumped, triply resonant, optical parametric oscillator. From the analysis of our experimental data, we conclude that the instability mechanism is different from the Hopf bifurcation predicted by the classical model of parametric interaction. Self-pulsing results from the interplay of a slow variable (temperature) and the optical bistability cycle, leading to a singularly perturbed system. From simple arguments, we propose a minimal dynamical model that reproduces well the observed behaviors.