Effect of applied electric fields on beam coupling in ferroelectrlcs

Abstract

Ferroelectrics, such as BaTiO3, have large electrooptic coefficients which make them useful photorefractive materials. Diffraction efficiencies in photorefractive materials are improved by the application of electric fields. In ferroelectrics, as in nonferroelectrics, the improvement in diffraction efficiency is attributable to increased drift. However in ferroelectrics at least one other mechanism contributes to the effect of electric fields on beam coupling. When an electric field is applied to a ferroelectric, even at room temperature, some polarization reversal (reversal of the c axis) takes place. Both mechanisms can cause the direction of optical gain to switch. We present a theory of the interaction of electric fields with ferroelectric materials and the consequences of these interactions on optical beam coupling via two-wave mixing.