Effects of polarization on wavefront shape in a LC-SLM diffractive feedback system

The effect of polarization on the phase distribution across a wavefront is discussed for a liquid crystal spatial light modulator based nonlinear diffractive single-feedback system. Theoretical analysis and numerical simulations show that when the polarization of the input light beam and interference effects are considered the form of the spectral phase ratio is altered considerably. It is found that this ratio can become zero or even negative for phase distributions with a wide range of spatial frequencies. This may have implications for high-resolution adaptive optics applications where, by careful choice of the polarization angle, very good suppression of phase distortions can be obtained. This can be achieved at relatively low feedback intensities and before the pattern formation threshold is reached.