2-WAVE MIXING AND FANNING EFFECT IN BI12TIO20 UNDER AN ALTERNATING ELECTRIC-FIELD

Numerical calculation of the two-wave mixing gain factor for arbitrary orientation of the holographic grating vector using the coupled wave theory developed for optically active electro-optic crystal enabling p ump-beam depletion is presented. Two-dimensional angular dependencies of the gain factor are measured in Bi12TiO20 photorefractive crystal u nder an alternating external electric field using the fanning effect. It is found experimentally that the angular distribution of fanning li ght is independent of the polarization state of the pump beam. This fa ct could not be explained by the existing theory.