Photorefractive properties of TNFM-sensitized PVK-based polymer composites and fully functionalized polymethacrylates

摘要

We have studied the photorefractive properties of (2, 4, 7-trinitro-9-fluorenylidene) malononitrile (TNFM) sensitized poly(N-vinylcarbazole)/N-ethylcarbazole polymer composites doped with 2-(3, 5, 5-trimethylhex-2-ene-1-ylidene)-1, 3-propanedinitrile and related dyes. Characterization included four-wave mixing experiments, two-beam coupling and photoconductivity measurements at a wavelength of 780 nm. At an applied field of 53 V/umm, we have observed complete internal diffraction and at 68 V/umm a gain coefficient of 230 cm~-1. Small alterations in the chromophore donor group substituents were used to tune the ionization potential of the dopant dye by 0.3 eV. They affected the grating build-up time, photorefractive phase shift, and complexatio with TNFM. This performance 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 observe net two-beam coupling gain and a diffraction efficiency of 60