Measurement of Spatial Phase-Shift in High Gain Photorefractive Materials

A. Grunnet-Jepsen, C. L. Thompson, and W. E. Moerner

The correct determination of the spatial phase-shift, fp, in photorefractive materials is crucial to the proper characterization of novel materials. It is shown that the grating translation techniques commonly used for the measurement of fp need to be reevaluated for high gain materials. Strong energy- and phase-coupling lead to non-uniform slanted gratings which result in an apparent dependence of the phase shift on the beam ratio and optical polarization. A revised theory is presented and analytical solutions are obtained for the special case of fp@p/2. Numerical solutions for arbitrary fpare in good agreement with measurements in a photorefractive polymer.