Highly Efficient Photorefractive Organic Polymers Based on Benzonitrile Shiff Bases Nonlinear Chromophores

Abstract

Photorefractive (PR) materials are ideal for potential applications in real-time optical processing. We report new highly efficient organic photorefractive polymers based on the nonlinear chromophores 4-[(4-(diethylamino)-2-hydroxybenzylideneamino]benzonitrile (Dc) and 4-[4-(diethylamino)benzylideneamino]benzonitrile (Ds). Holographic experiments in a four wave mixing (FWM) and two beam coupling (TBC) geometries were carried out by using a He–Ne laser (633 nm). The electric field steady-state diffraction efficiency dependence was measured. Diffraction efficiency as high as 90% was observed for polymers based on Dc at 25 wt % doping level at an external applied electric field around 56 V/μm. For compounds Dc and Ds, the μβ product was also measured by EFISH technique, Dc presents a value 3.5 times higher than Ds, which is supported by a theoretical prediction; structural X-ray data and their effect on the PR performance are also discussed. Reversible holographic imaging by using these efficient PR polymers is presented.