Optical bistability in photorefractive four-wave mixing

Abstract

The coupled wave equations for four-wave mixing (FWM) in a cubic, non-optically-active photorefractive crystal are solved for the case of orthogonally polarized pumping beams. For certain values of the pump and probe beam intensity ratios, the solutions exhibit a multi-valued branching behavior. If the different branches are assumed to be stable, bistability of the phase conjugate reflectivity is predicted. Furthermore, it is shown that this solution is valid for the case where the pump beams are parallel-polarized if the geometry of the four-wave mixing configuration is modified slightly. Our results are therefore applicable to crystals of other symmetry groups, such as barium titanate, using the modified FWM configuration.