THEORY OF INCOHERENT SELF-FOCUSING IN BIASED PHOTOREFRACTIVE MEDIA

A theory describing propagation and self-focusing of partially spatial ly incoherent light beams in nonlinear media is developed. It is shown that this process is effectively governed by an infinite set of coupl ed nonlinear Schrodinger-like equations, provided they are initially a ppropriately weighted with respect to the incoherent angular power spe ctrum of the source. The particular case of spatially incoherent beam propagation in biased photorefractive media is considered in detail. N umerical simulations indicate that spatial compression as well as self -trapped states are possible under appropriate conditions. Our results are in good agreement with recent experimental observations.