Measurement of Photorefractive Two-Wave Coupling Exponential Gain Coefficient of LiNbO₃ : Fe Crystal

For a photorefractive crystal, the exponential gain coefficient of two-wave coupling,Г, is a constant. In this paper, the constant Г of a LiNbO₃: Fe crystal is measured by using Gaussian beams and quasi-uniform beams. The difference between the results is attributed to the self-defocusing effect of the crystal.