Highly efficient photorefractive polymers doped with cyano nonlinear chromophores

摘要

In this work we report new highly efficient organic photorefractive polymers based on aryl-cyano non-linear chromophores [(4-(diethylamino)-2-hydroxybenzylideneamino]benzonitrile (CN-C-OH) and [4-(diethylamino) benzylideneaminojbenzonitrile (CN-S-OH). The PR polymer blends are composed by the photoconductor poly (9-vinylcarbazole) and plasticizer 9-ethylcarbazole PVK:ECZ matrix, as well as the sensitizer fullerene C_(60) Holographic experiments in a tilted four wave mixing (FWM) and two beam coupling (TBC) geometry were carried out by using a 10 mW He-Ne laser (633 nm). The experiments were performed at room temperature to measure the electric field steady-state diffraction efficiency dependence of the PR composites. High diffraction efficiency as high as 90 % was observed for polymers based on CN-C-OH at 25 wt. % doping level and an external applied electric field around 56 V/μm. The μβ product was also measured by EFISH technique for compounds CN-C-OH and CN-S-OH, results showed that CN-C-OH present a value 3.5 times higher than CN-S-OH, which is supported by a theoretical prediction. Demonstration of fast reversible holographic imaging (～0.5 s) by using these highly efficient organic photorefractive polymers based on CN-C-OH and CN-S-OH is presented.