Characterization of PVK-based photorefractive polymers by photo-EMF technique in reflectance configuration

Summary form only given. Characterization of photorefractive polymer films is a complicated problem because of the dependence of many relevant parameters, such as photocarrier generation rate, their life-time, and diffusion length, on the external field E/sub 0/. Especially difficult are investigations at low E/sub 0/ values, where holographic measurements are not reliable because of low diffraction efficiency. We report experimental data on characterization of a polymer film in photo-EMF configuration, which allows us to probe the space-charge grating even without application of the external field. Unlike similar dependence in photorefractive crystals (in BSO in particular) field dependence of the photo-EMF signal U/sup /spl Omega//(E/sub 0/) does not reach zero level exactly. We attribute this to proximity of /spl Omega/ used to one of the cut-off frequencies. Another explanation is the dispersion of all electrical parameters in amorphous systems.