Influence of nonlinearities on two-wave mixing in photorefractive InP : Fecrystals with a moving grating

Two-wave mixing in photorefractive InP:Fe crystals is revisited in terms of an externally applied de field combined with the moving-grating technique. We show that the disagreement between theory and experiment that was previ ously observed in the literature can be reconciled by an examination of the influence of both the absorption along the propagation axis and the nonlin earities that occur at relatively large fringe modulations. A finite-differ ence method is used to demonstrate the dependence of these nonlinearities o n the average incident intensity. (C) 2000 Optical Society of America [S074 0-3224(00)00403-3] OCIS codes: 160.5320, 190.7070.