Fraunhofer diffraction pattern of a Gaussian beam passing through a photorefractive crystal BGO

Abstract

In this theoretical-experimental study, we use the Fresnel-Kirchhoff diffraction theory to simulate the formation of the far-field diffraction pattern of a divergent Gaussian beam propagated through a BGO photorefractive crystal. We show that for the BGO photorefractive crystal, in addition to the wavefront curvature and the change in the refractive index of the medium due to the light intensity, there is a third contribution affecting the medium-induced nonlinear phase shift; the latter is related to the additional change in the refractive index produced by the photorefractive effect.