PHOTOREFRACTIVE RECORDING IN BTO IN THE NEAR-INFRARED

An enhancement of the beam coupling in the near infrared is observed i n Ba12TiO20 preexposed to visible light. The experiments indicate that photorefractive nonlinearity in this spectral range is determined by the diffusion charge transport. To explain the oscillations in the tra nsmitted beam intensities we consider a model with two types of moving species (electrons and holes) and several charge traps. It is shown t hat the optical excitation energy for deep centers is roughly 2 eV.