Photorefractive properties and applications of polymer composites and fully functionalized polymethacrylates

We have studied the photorefractive properties of (2,4,7-trinitro-9-fluorenylidene)malononitrile (TNFM) sensitized poly(N-vinylcarbazole) (PVK)/N-ethylcarbazole (ECZ) polymer composites doped with two structurally related chromophores. Characterization included four-wave mixing experiments, two-beam coupling and photoconductivity measurements at a wavelength of 780 nm. At an applied field of 48 V/μm, we have observed complete internal diffraction and gain coefficients exceeding 120 cm−1. A small alteration in the chromophore donor group substituents was used to tune the ionization potential of the dopant dye. This affected the grating build-up time and photorefractive phase shift. As an application, we demonstrate the operation of a photorefractive novelty filter using a 120-μm-thick sample. The performance of the polymer composites is compared to that of three newly synthesized polymethacrylates functionalized with carbazole, a dodecyl chain as an internal plasticizer and three different dyes. Here, we have observed net two-beam coupling gain and a diffraction efficiency of 60% at 58 V/μm.