Abstract

The process of unstationary enhancement of the photorefractive effect through the application of square-wave ac electric fields is described. By examining the charge transport equations governing the photorefractive response, we show that this response is strongly dependent upon the frequency of the applied ac field and exhibits a maximum when the period of oscillation is between the photorefractive response time, τ_p, and the charge recombination time in the medium, t_R. From this analysis we obtain a simple expression for the conditions for maximum response and show that the optimal oscillation period behaves as T = Const. × (τ_p² t_R)^1/3. These results are compared to those of earlier analyses of ac field enhancement and with experimental results in BSO.

© 1992 Optical Society of America