Electrooptical control of light beams in photorefractive crystals
Belarusian State University, Belarus
This paper demonstrates the variant of interaction between two light beams on going from parallel to the orthogonal geometry in cubic photorefractive crystals under the effect of an external electric field. In this geometry the self-deflection effect of a probe beam has been realized experimentally and the conditions for its compensation due to the local crystal illumination by an additional control beam have been found. The exposure required to form the stable structure of a probe beam has been established; the beam deflection angle was determined depending on the center distance between the light beams. Based on the results obtained, the possibility for estimation of a local light-induced change in the refractive index has been shown. To describe and generalize the processes proceeding within photorefractive media, a theoretical model has been proposed including the conduction band, valence band, and the band gap with deep-short-and long-lived trapping levels and with the trapping center close to the conduction band bottom. This model offers an adequate description of the kinetics for the photoconductivity and photoinduced electron redistribution initiated by nanosecond pulses.