Photorefractive properties and applications of polymer composites and fully functionalized polymethacrylates

We have studied the photorefractive properties of (2,4,7-trinitro-9-fluoren ylidene)malononitrile (TNFM) sensitized poly(N-vinylcarbazole) (PVK)/N-ethy lcarbazole (ECZ) polymer composites doped with two structurally related chr omophores. 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/mum, we have observed complete internal diffractio n and gain coefficients exceeding 120 cm(-1). A small alteration in the chr omophore donor group substituents was used to tune the ionization potential of the dopant dye. This affected the grating build-up time and photorefrac tive phase shift. As an application, we demonstrate the operation of a phot orefractive novelty filter using a 120-mum-thick sample. The performance of the polymer composites is compared to that of three newly synthesized poly methacrylates 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/mum. (C) 2001 Els evier Science B.V. All rights reserved.