Photorefractive processes in polymers and organic-inorganic glass composites

We report on the studies of three photorefractive (PR) polymeric systems: two different multifunctinal polymeric composites and one doped polymer. The doped polymer system consisted of charge transporting polymer, a plasticizer, a photocharge generation sensitizer, and a second-order nonlinear optical chromophore. The measurements of the electric field and light fluency dependencies of charge photogeneration efficiency, response speed, carrier mobility and diffraction efficiency provided information about the kinetics of the photorefractive effect. The two new multifunctional photorefractive polymers each contains a second-order nonlinear chromophore and a charge transporting molecule covalently attached to the polymer backbone (methacrylate chain or silica). The charge transporting and the second- order NLO segments of the polymer are the N-alkylated carbazole group and the stilbene derivative, respectively. Fullerene C ₆₀ or charge transfer complex of trinitrofluorenone:carbazole was utilized as charge generating sepcies. The specific advantages of sol-gel processing of organically modified silanes render optical quality materials having the properites of both oxide glass and organic compounds. Electro-optic and PR responses in these composites have also been measured.