High photorefractive performance of low glass-transition-temperature polymeric composite doped with bifunctional chromophore

We report a novel optimized nonlinear optical chromophore, 1-n-butoxyl-2,5-dimethyl-4-(4'-nitrophenyl-azo)benzene (BDMNPAB), that acts effectively as both electro-optic chromophore and plasticizer in a low glass-transition-temperature photorefractive polymeric composite. In the polymeric composite of BDMNPAB:poly(N-vinylcarbazole) (PVK):2,4,7-trinitro-9-fluorenone in a weight ratio of 44.55:1, the glass transition temperature was lowered to 43 degrees C. Two-beam coupling gain as high as 195 cm(-1) and an index grating amplitude of about 4.3 x 10(-3) were obtained. Furthermore, high solubility of the dye in PVK and high stability of the photorefractive composite were also exhibited.