Parametric four-wave processes in photorefractive crystals

Abstract

A theory of polarization-dependent four-wave processes is developed for photorefractive nonlinear media. It includes the classification of possible elementary nonlinear processes, an analysis of their polarization and geometric properties, and a unified technique for the calculation of wave amplitudes. The theory is applied to the description of different types of conical scattering in BaTiO3 and LiNbO3 crystals. Effects of crystal anisotropy, angular and frequency detunings for interacting waves are taken into account. A good agreement between theory and experiment is demonstrated. Applications of the theory to treatment of a number of important photorefractive effects are considered.