CRITICAL BEHAVIOR OF ANDERSON LOCALIZATION UNDER SATURABLE SELF-DEFOCUSING NONLINEARITY

Abstract

We theoretically investigate the optical Anderson localization in the disordered photorefractive lattices under different strength of saturable self-defocusing nonlinearity. Via continuously increasing the value of the nonlinear parameter and applying numerical simulations respectively, a critical behavior, a transformation from a localized state to a spreading state, is found. We use different initial power of the probe and obtain a series of critical values of the nonlinear parameter. Below the critical value, the localizing effect is enhanced with the increase of the nonlinear parameter. While above the critical value, the localized state is destroyed. We give a study of the critical behavior and the critical values corresponding to different physical parameters, including the intensity of the self-defocusing nonlinearity, the intensity of the lattice-forming beams and the randomness strength of the structure.