Thiapyrylium dye sensitization of photorefractivity in a polymer composite

An ionic thiapyrylium dye has been used as a photocharge sensitizer for the first time in a photorefractive polymer composite containing poly(9-vinylcarbazole) and 4-(N,N-diethylamino)- (β)-nitrostyrene. Photorefractive gratings are written at a wavelength of 703 nm and four-wave mixing diffraction efficiencies as high as 2% have been achieved in films less than 200 μm thick. Asymmetric energy transfer has been observed and a two-beam coupling gain of 7 cm−1 has been obtained. Holographic image recording and retrieving have also been demonstrated.