DETERMINATION OF THE PHOTOREFRACTIVE PARAMETERS OF BI12SIO20 BY STUDYOF THE DYNAMIC BEHAVIOR OF COMPLEMENTARY GRATINGS

The dynamic behavior of the complementary space-charge gratings formed in a Bi12SiO20 crystal through prolonged recording at 780 nm is used to determine a number of significant photorefractive parameters, inclu ding effective trap density, diffusion length, and dielectric relaxati on time, simultaneously for both types of charge carriers. This simple , all-optical method does not require prior knowledge of any other pho torefractive parameters and therefore represents the only procedure cu rrently available capable of direct materials evaluation in the low-co upling regime. Furthermore, the scheme provides the means for quantita tively assessing the effects of crystal sensitization resulting, for e xample, from uniform preillumination. (C) 1998 Optical Society of Amer ica.