SIGNATURE OF MEMORY FOR PHOTOREFRACTIVE 2 BEAM COUPLING - COMPUTATIONAL AND EXPERIMENTAL RESULTS

We have conducted numerical calculations describing photorefractive tw o beam coupling under high gain conditions and compared them with expe rimental results generated in our laboratory. A complete modeling of t he photorefractive rate equations, which generalizes the modeling to i nclude nonlinear terms and relaxes the non-depleting pump approximatio n, demonstrates a memory effect in the time dependence of the two beam coupling gain. This memory effect shows that time dependence of the t wo beam coupling gain is characterized by an 'S' curve. In addition, t he nonlinear terms contribute a tail in the growth of the two beam cou pled signal which results in predicted gains about 10% higher than exp ected for the linear model. Experimental results are shown to agree wi th the modeling. (C) 1998 Elsevier Science B.V. All rights reserved.