High-performance polysiloxane-based photorefractive polymers with nonlinear optical azo, stilbene, and tolane chromophores

The performance of photorefractive (PR) polymers strongly depends on the incorporated nonlinear-optical chromophores. We compare three polysiloxane-based PR guest-host polymers with an ate, a stilbene, and a tolane type of chromophore. Characteristic properties such as diffraction efficiency eta, gain coefficient Gamma, phase shift phi, modulation of the index of refraction an, and response time are measured as a function of the external electric field. Orientational enhancement as well as the influence of photoisomerization is observed and analyzed quantitatively. The materials show high performance with Delta n > 1 x 10(-2), corresponding to external diffraction efficiencies of 60% for samples of only 40-mu m thickness. (C) 1998 Optical Society of America.