Study of beam-fanning hysteresis in photo- refractive SBN:Ce: light-induced and primary scattering as functions of polar structure
We study light-induced scattering (beam-fanning) in the photorefractive crystal SBN:Ce as a function of the polar structure of the crystal. The spatial structure of the beam-fanning is measured at different externally applied electric fields, and an optical hysteresis is found in the scattering. It is shown that the scattering hysteresis results from a polarization hysteresis typical for ferroelectrics in the polar phase. New information about primary scattering in SBN is obtained, and a corresponding model of its origin is proposed. It is shown that the intensity and angular distribution of the primary scattering strongly depend on the polar structure of the crystal and can be affected by the subsequent action of an external field and coherent illumination.