Polarization properties of self-diffraction in sillenite crystals: reflection volume gratings

Abstract : We study two-beam interaction in photorefractive sillenite crystals in reflection geometry and derive analytic expressions for the signal gain and its polarization direction in the presence of a strong pump beam. The crystal is cut normal to one of the crystallographic axes, and no external electric field is applied. Crystal absorption and its natural optical activity are taken into account. The coupling effects are strongly dependent on the polarization directions of the interacting beams. We determine the optimal polarization directions and optimal crystal thickness that give maximum signal gain. Experimental results are in excellent agreement with theoretical calculations.