Spatial selectivity of a four-wave radiation converter based on thermodiffusion and electrostriction mechanisms of nonlinearity

An analytic expression allowing to analyze the spatial selectivity of the four-wave converter based on thermodiffusion and electrostriction nonlinearities is obtained. Shown that the treatment of electrostriction leads to two object waves at small spatial frequencies in opposite phase with the waves that occur due to thermodiffusion nonlinearity. There is a spatial frequency at which the reflectivity of these waves is zero.