Diffraction of Light by Ultrasound in Acoustically Anisotropic Medium

The paper is devoted to investigation of Bragg diffraction of light by ultrasound propagating in media possessing strong anisotropy of acoustic properties. It is shown that acoustic anisotropy of crystals influences on the process of light and sound interaction. In case of Bragg regime of acousto-optic interaction, intensity of diffracted light and frequency bandwidths of diffraction in the crystals differ from corresponding diffraction efficiencies and acoustic bandwidths in glass materials. During intermediate between Bragg and Raman-Nath regimes of interaction at normal incidence angles, a symmetry of optical intensity distribution over positive and negative diffraction maximums is broken. As a result of the performed research, unknown regimes of acousto-optic interaction provided by acoustic anisotropy of crystals are predicted. For example, collinear isotropic diffraction and interaction with low sensitivity to divergency of acoustic beams are described in the paper.