Polarization of diffracted optical wave in the case of acousto-optic diffraction on the longitudinal acoustic wave in fused silica

. We report on polarimetric studies for the diffracted light originated from acousto-optic (AO) diffraction at a longitudinal acoustic wave. A particular case of intermediate Bragg–Raman–Nath diffraction regime in fused silica is considered. We find that for the incident circularly polarized optical waves the ellipticity of the diffracted wave is determined by the ratio of elasto-optic coefficients p 11 and p 12 , while for the incident linearly polarized waves this ratio is determined by the azimuth of diffracted wave. The ratio of coefficients determined in this way agrees well with the literature data. We detect a small deviation from linear polarization for the diffracted optical waves under condition when the incident waves are linearly polarized. This deviation can be caused by changing phase difference of the diffracted eigenmodes.