Measurement of Spatial Phase-Shift in High Gain Photorefractive
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.