Orientation and polarization effects of two-beam coupling in a cubic optically active photorefractive piezoelectric BSO crystal

We consider in detail the piezoelectric properties and the optical activity of (110)-cut cubic photorefractive crystals with respect to the optimization of two-beam coupling. An expression is obtained for the azimuth of two interacting linearly polarized waves at which the maximum energy exchange occurs. The expression for the maximum intensity of one of the waves is also obtained. It is shown that for each light-wave azimuth there are three local energy-exchange maxima, corresponding to three different orientations of the grating vector in the cut plane. The optimum conditions for energy exchange in a BSO crystal with thickness d = 2.19 mm are realized at azimuths ψ ≅ 23° and ψ ≅ 13° for orientation angles θ ≅ 55° and θ ≅ 305°, respectively. The results of the experimental study of two-beam coupling in BSO are in good agreement with theory.