Optical topographic technique to material characterization of photorefractive crystals

摘要

Nonlinear transmission wave-mixing problem in a photorefractive medium that include both local and non-local responses is solved not traditionally but with using a new variable namely the dynamic grating amplitude. The dynamics of the wave-mixing is described by a modified sine-Gordon equation that have soliton-like solutions for the dynamic grating amplitude. For the first time the solution for the grating amplitude distribution in a medium with complex response is obtained. The shape of the grating amplitude profile is determined only by the value of the non-local response in the steady state, and both by local and by non-local components of the response in a transient process. Complete analytical solutions with taking into consideration the complex medium response as well as the absorption in two-wave mixing are obtained. The described theoretical predictions can be a base for a novel topographical method to material characterization of photorefractive crystals that allows one to study contributions local and non-local components of the medium response more precisely.