TEMPERATURE-DEPENDENCE STUDIES OF PHOTOREFRACTIVE EFFECT IN A LOW GLASS-TRANSITION-TEMPERATURE POLYMER COMPOSITE

The temperature dependence of the photorefractive effect in a polymer composite containing poly(9-vinycarbazole), tricresyl phosphate, buckm insterfullerene, and 4-(N,N-diethylamino) -beta-nitrostyrene is presen ted. The photoconductive, electro-optic and photorefractive properties of the material have been studied in the temperature range of 22-61 d egrees C. An apparent increase of electro-optic modulation with temper ature and its eventual saturation is observed. This behavior is attrib uted to the temperature activated orientational mobility of the second -order nonlinear chromophores. The polarization anisotropy between the p-and s-polarized readouts is consistent with what would be expected on the basis of directly measured effective electro-optic coefficients . By correlating the electro-optic value with the diffraction efficien cy, the temperature dependence of the space-charge field is obtained a nd explained by temperature dependencies of the dark conductivity and the photoconductivity of the material. (C) 1997 American Insitute of P hysics.