Acoustooptic interaction of weakly divergent Gaussian beams in strongly anisotropic media

Anisotropic acoustooptic diffraction of a bounded Gaussian beam is considered in a three-dimensional setting with Bragg's diffraction. We derive a system of equations that relates the Fourier transforms of the transmitted and diffracted light amplitudes and the sound beam propagating in the anisotropic medium with a drift of acoustic energy. Simultaneously, we take into account the anisotropic spread of the propagating acoustic beam. Solving these equations subject to the respective boundary conditions, we obtain a formula for the relative magnitude of diffraction as a function of the drift angle and the divergence of the acoustic beam in both planes. This formula is valid for any direction of polarization of the incident and diffracted light beams.