Abstract

Enhancements in the two-beam coupling gain can be achieved in cubic crystals of the BSO type by the use of nonstationary external conditions such as the application of a dc field along with a moving interference pattern or by the application of an alternating electric field[1,2,3,4,5]. However, for modulation index, m, greater than about 0.1 the performance falls off significantly with increasing m[1,5]. Some success has been achieved in obtaining steady-state solutions of the nonlinear equations in the presence of moving fringes[1,6,7,8]. These numerical calculations were accomplished by expansion of the variables into their Fourier components or by perturbation techniques. In this paper we model the photorefractive grating formation by a finite difference method. This approach is quite general. The numerical solutions predict the photorefractive behavior at large modulation for stationary and nonstationary photorefractive recording techniques.

© 1991 Optical Society of America