Optical nonreciprocity of counterpropagating light waves under Bragg diffraction conditions in gyrotropic cubic crystals

The coupled waves method is used in a calculation of the phase and amplitude nonreciprocity of counterpropagating light waves in the case of the acousto-optical interaction in gyrotropic cubic crystals. The dependences of the phase and amplitude nonreciprocities on the state of polarisation of light and on the gyrotropy parameter are determined for the Bragg diffraction by a shear ultrasonic wave. Numerical calculations are reported for a bismuth silicate (Bi₁₂SiO₂₀) crystal in the absence and the presence of the acousto-optical diffraction feedback.