High-frequency branch of space-charge waves in photorefractive crystals

Abstract

Space-charge waves have been investigated in the sillenite-type crystals Bi12SiO20, Bi12GeO20, and Bi12TiO20. For the experiments, oscillating light patterns and the effects of spatial and overall rectification have been utilized. Main attention has been paid to the high-frequency branch and to the detailed comparison of experiment and theory. It was found that the theoretical model describes the experimental results for the high- and low-frequency branches quite reasonably; in particular, the dispersion laws are confirmed. By use of the data obtained for both branches, the major characteristics of the crystals (lifetime of the carriers, mobility, Maxwell relaxation time, and screening factor) have been determined. (c) 2005 Optical Society of America.