Diffusion recording in photorefractive sillenite crystals: an analytical approach for engineering purposes

Simple formulae fur the two-wave mixing (TWM) gain and diffraction efficien cy obtained in the approximation of weak coupling and strong optical activi ty allow us to tune the experimental setup for interferometric applications . We prove that two invariant parameters, trace and determinant of the coup ling tensor, are sufficient to optimize the experimental setup. Both practi cally important crystal cuts, (110) acid (111), can be treated in a unified manner. Fundamental TWM properties (90 degrees-jumps of the optimum polari zation, apparent doubling of the local maxima of the diffraction efficiency in comparison with the gain, drastic changes between regimes of small and large polarization rotation, the crucial role of elastooptic properties) ar e systematized. The guidelines for the design of an optimum experimental se tup for interferometric applications including anisotropic self-diffraction using sillenite crystals are presented. Quantitative agreement with previo us experimental data is demonstrated. (C) 2000 Published by Elsevier Scienc e B.V. All rights reserved.