Efficiency of photorefractive diffraction in electro-optic and optically active sillenite crystals

We study the diffraction efficiency of volume phase gratings in photorefractive sillenite crystals, such as Bi12GeO20, Bi12SiO20 and Bi12TiO20, when the grating vector makes an angle with the 〈110〉 axis. Analytic expressions for the diffraction efficiency of the diffracted light have been derived taking into account the optical activity, field-induced linear birefringence, piezoelectric and photoelastic effects, when linearly polarized light is incident normally on the crystal. Experimental results are given.