Photorefractivity in a novel polymer composite with high diffraction efficiency and broad optical transparency

A novel photorefractive polymer composite has been developed in which a new organic dye, 4-[N-(2-hydroxyethyl)-N-methylamino]-4′-[(6-hydroxyhexyl)sulfonyl] stilbene, is used as a second-order nonlinear optical chromophore together with poly(N-vinylcarbazole) as the hole-transporting matrix, tricresyl phosphate as a plasticizer, and C₆₀ as a photosensitizer. The photoconductive, electro-optic, and photorefractive properties of the material have been experimentally studied at wavelengths of 488, 514.5, and 632.8 nm. The amplitude and the phase dependencies of the electro-optic response have been investigated. The composite shows high photorefractivity over a broad wavelength range. Diffraction efficiencies between 20% and 40% as well as net two-beam coupling gains of 25-65 cm^-1 have been obtained at wavelengths of 488, 514.5, and 632.8 nm.