Determination of the photorefractive parameters of Bi12SiO20 by study of the dynamic behavior of complementary gratings

The dynamic behavior of the complementary space-charge gratings formed in a Bi(12)SiO(20) crystal through prolonged recording at 780 nm is used to determine a number of significant photorefractive parameters, including effective trap density, diffusion length, and dielectric relaxation time, simultaneously for both types of charge carriers. This simple, all-optical method does not require prior knowledge of any other photorefractive parameters and therefore represents the only procedure currently available capable of direct materials evaluation in the low-coupling regime. Furthermore, the scheme provides the means for quantitatively assessing the effects of crystal sensitization resulting, for example, from uniform preillumination. (C) 1998 Optical Society of America.