Incoherent modification of polarization gratings in photoanisotropic media

The influence of an incoherent wave on polarization gratings written in a p hotoanisotropic material is investigated. For the example of a polarization grating written with two orthogonal circular polarized waves the diffracti on efficiency was found to change by adding a third incoherent wave. A theo retical description of the modified grating is given. Using a simple model the alteration of the diffraction efficiency is estimated and found to be i n good agreement with the experimental results. (C) 2000 Elsevier Science B .V. All rights reserved.