Effect of Optical Activity on Degenerated Four-Wave Mixing in Cubic Photorefractive Crystal

Abstract

A system of coupled waves equations for calculation the vector amplitudes of linearly polarized light waves during their degenerate contra-directional four-wave mixing in cubic photorefractive crystals of 23 and $\bar {4}3m$ symmetry classes in general spatial orientation was obtained. Linear electrooptic, photoelastic, and inverse piezoelectric effects, as well as natural optical activity, absorption and circular dichroism are taken into consideration at the theoretical modelling. The dependencies of intensity of p- and s-components of the phase-conjugated wave on the crystal orientation angle and the thickness of one at different polarization azimuths of the signal wave for GaAs and Bi₁₂SiO₂₀ crystals of (110)-cut are analyzed. It is shown that these dependencies for Bi₁₂SiO₂₀ crystal exhibiting optical activity differ from the ones derived for optically non-active GaAs crystal. It takes place since under the combined action of the induced anisotropy and optical activity, the conditions of diffraction of the light waves during their four-wave mixing by holographic gratings formed in the Bi₁₂SiO₂₀ crystal will be different with respect to ones in GaAs. It is established that the effect of optical activity on intensity of the phase-conjugated wave considerably depends on the values of the crystal orientation angle, thickness, and polarization azimuths of the signal wave. Optical activity can lead to both decreasing and increasing of intensity of the phase-conjugated wave in dependence on the conditions of holographic experiment.