Determination of the Optimal Spatial Orientation of Bismuth Titanate in Forward Four-Wave Mixing

Abstract

We report a study of the dependence of the optimized reflection coefficient in forward four-wave mixing on the spatial orientation of bismuth titanate. The formation of three holographic gratings with a phase–amplitude structure is examined during the interaction of light waves in a photorefractive crystal. Calculations are performed taking into account the anisotropy of the linear electro-optical, photoelastic, and inverse piezoelectric effects, as well as the optical activity, linear absorption, and circular dichroism of the crystal. It is shown that the efficiency of phase-conjugation diffraction in bismuth titanate depends markedly on the crystal sample cut. It is found that when using a Bi₁₂TiO₂₀ crystal with a (111) cut, the reflection coefficient reaches 95% of the maximum possible value that can be obtained with the optimal spatial orientation of the bismuth titanate. The use of a crystal sample with (100) and (110) cuts leads to a nearly twofold decrease in the optimized reflection coefficient compared to the case of applying a crystal with a (111) cut.