Photorefractive effects and light‐induced charge migration in barium titanate

摘要: We propose a new theoretical model for the light‐induced migration of charges which mediates ’’photorefractive effect’’ (light‐induced refractive index change) in barium titanate and other crystals. also present experimental results various effects this charge single‐domain crystal titanate, specifically, (1) energy transfer between two intersecting optical beams, (2) four‐wave mixing optical‐beam phase conjugation, (3) erasure spatial patterns photorefractive variations, (4) photoconductivity. The predicts observed dependences these on beam intensities, directions, polarizations, orientation, an externally applied dc electric field. Time transients as well steady‐state magnitudes are predicted. In model, identical migrate by hopping adjacent sites, with rate proportional to total light intensity at starting site. net varies local potential that is calculated self‐consistently from pattern. positive density (1.90.2) ×1016 cm−3 514 nm. origin sites unknown. constant determined interactions used predict photoconductivity 1.3×10−10 cm Ω−1 W−1