Photoinduced birefringence and diffraction efficiency in azo dye doped or grafted polymers: theory versus experiment of the temperature influence

We have investigated the influence of the temperature on the photoinduced b irefringence as well as on the diffraction efficiency of azo dye doped or g rafted polymers. The samples are composed of three polymer matrices contain ing 2,5-dimethyl-4-(p-nitrophenylazo anisole). We propose two theoretical m odels to explain the experimental increase of both phenomena when the tempe rature is decreased. Models are based on the statistical angular distributi on of the chromophores that depends on the intensity of the polarized laser beam in the media, counteracted by the thermal agitation. Parameters intro duced in both models can be used to characterize the polymeric system prope rties. (C) 2000 Optical Society of America [S0740-5224(00)02204-9]. OCIS co des: 090.2900, 160.4890.