Volkov A. Vectorial wave mixing in low symmetry photorefractive media.

The vectorial mixing of coherent optical waves in the monoclinic photorefractive crystals like Sn2P2S6 have been studied. All components of the Pockels tensor of Sn2P2S6 have been estimated comparing the efficiency of the vectorial wave mixing processes which use identical photorefractive gratings. The possibility of gain factor increasing for counterpropagating light beams by means of their appropriate orientation in more than 2.6 times as compared to the standard geometry is demonstrated from the theoretical and experimental data. The beam fanning in Y-cut Sn2P2S6 crystal has non-uniform polarization structure which depends on the laser beam polarization and is caused by only the optical properties of the sample.