INTENSITY REDISTRIBUTION IN A THIN PHOTOREFRACTIVE CRYSTAL CAUSED BY STRONG FANNING EFFECT AND INTERNAL REFLECTIONS

Propagation of the light beam in a thin photorefractive crystal with t he diffusion-type mechanism of nonlinearity has been studied both expe rimentally and theoretically. Total internal reflections of fanned bea ms from the crystal's side surfaces and their coupling with the pump b eam result in the light-intensity redistribution and in the generation of the photorefractive surface wave. We propose a theoretical model o f the intensity redistribution that considers the light-energy flow fr om the pump beam to the fanning beam and backward after the fanning be am reflection. A numerical simulation shows that the total internal re flection off the surface, toward which the flow of the light energy is directed, is responsible far the light-energy self-concentration. (C) 1996 Optical Society of America.