Effect of applied electric field on the buildup and decay of photorefractive gratings

We have measured the real and imaginary parts of the experimental rate constant of the buildup and decay of photorefractive charge gratings in cubic crystalline insulating Bi12SiO20, in the presence of an externally applied voltage. The value of the resulting field in the crystal was monitored using the crystal´s own electrooptic effect. We found agreement over our entire range of fields (0-3 kV/cm) with the predictions of Kukhtarev who postulated that electrons are optically excited from a single species of trap to a single conduction band where they drift and diffuse before experiencing direct recombination to an empty trap. At the higher fields, the expected slowing of the writing and erasure processes by a factor of 20 was observed.