Theory of two-center transport in photorefractive media for low-intensity, continuous-wave illumination in the quasi-steady-state limit

Abstract

A two-center photorefractive model permitting all center-to-band transitions and electron-hole charge transport unifies several models describing subsets of these transitions. Using the quasi-steady-state approximation for low continuous-wave illumination, the model derives the first-order Fourier harmonic of the steady-state space-charge distribution and fields and the corresponding response rates. The model describes electron-hole competition, complementary gratings, double-exponential time-dependent behavior, and nonlinear dependence of response rates on intensity. The model can be used to make new predictions of photorefractive behavior of crystals in which two species of impurity center are present; an example is presented for BaTiO3.