Analogy between photorefractive oscillators and class-<i>A</i>lasers

Abstract

Photorefractive oscillators are shown to have the same transverse properties as class-A lasers, in spite of the different mechanisms of light amplification in both systems and the different microscopic physics. A laser Ginzburg-Landau equation for the order parameter of photorefractive oscillators (PRO) is derived and correspondences between parameters of PRO's and class-A lasers are given. The close similarity between these two systems is evidenced by numerical calculations. Experimentally, a PRO is found to emit stationary patterns such as pure mode patterns and vortex lattices, and to display a periodic motion of vortices, all of which are characteristic of lasers.