Anomalous frequency pulling in the photorefractive oscillators

The emission frequency of an optical oscillator is not, in general, the cav ity frequency, because it results from a compromise between the cavity and the material (atom, crystal) frequencies: this phenomenon is known as frequ ency pulling. We study in this paper the mechanisms leading to frequency pu lling in oscillators with photorefractive gain (OPG), and compare them with those of lasers. We find that because the pulling in OPG does not depend e xplicitly on the empty cavity mode frequency, behaviors different from thos e observed in lasers are obtained. In particular. for a given set of parame ters, the frequency pulling has a constant sign, so that the emission frequ ency is always larger (or smaller) than the maximum gain frequency. This le ads to the counterintuitive effect that, in some conditions, the emitted in tensity could decrease as the losses are decreased. [S1050-2947(99)09908-4] .