Origin of Sublinear Photrefractive Effects in Barium Titanate

Abstract

The band-transport model of Kukhtarev [1] is commonly used to describe the photorefractive grating formation. According to this model the grating formation time should be inversely proportional to the laser intensity. However, experiments performed on barium titanate have shown a response time which has varied with intensity as I−x, where the exponential factor x has ranged from 0.5 to 1.0.[2] In this paper we show by computer modeling of the grating formation that the sublinear dependence of the response time is accounted for by the presence of secondary photorefractive centers.