Self-oscillation in a photoreactive phase-conjugate mirror with linear absorption .1. Isotropic four-wave mixing

The effects of linear absorption on the degenerate and nondegenerate self-oscillation conditions of a photorefractive phase-conjugate mirror are explored. In this study, phase-conjugation results from nonlinear mixing of two strong undepleted parallel-polarized counterpropagating pump waves with a probe wave. Numerical results are presented that illustrate that the linear absorption tends to increase the value of the coupling coefficient required for self-oscillation. It is also found that the pump intensity ratio r is almost independent of the Linear absorption for positive normalized detuning Delta omega tau between the probe and the pump frequencies and of the zero phase shift, phi, between the gratings and the light interference patterns when the gratings are stationary. For phi = +/-pi/2 the variation of r with respect to absorption is symmetric for positive and negative detunings. (C) 1996 Optical Society of America.