Model of the self-Q-switching instability of passively phased fiber laser arrays

Abstract

A simple physical model is presented to explain observed self-pulsations in passively phased rare earth-doped fiber laser arrays. Their essential features are the feedback level’s sensitivity to small perturbations in the phases of array fields, hence altering the cavity’s Q-value, and the nonlinear changes in the refractive index of the amplifier gain media. The model’s qualitative prediction for an array having at least two elements that is operated at sufficiently high power levels, of the growth of an initial disturbance, is confirmed by a linearized stability analysis of the field and medium equations.