Temperature- and light-induced relaxation of the electro-optic properties of poled side-chain copolymers

We report on the measurement of the time relaxation of the electro-optic properties of poled side-chin copolymers under illumination with absorbed laser radiation. Films of side- chain Disperse Red 1 substituted poly-Methyl-Methacrylate were sandwiched between ITO and gold electrodes and poled with a standard temperature/electric field cycle. The decay of the electro-optic properties, measured by means of the Teng and Man ellipsometric reflection technique at (lambda) equals 830nm, was measured for several intensities of a circular polarized absorbed laser beam, (lambda) equals 514.5nm, illuminating the sample. The relaxation shows a stretched exponential time dependence, with intensity dependent decay and stretching constants. The relaxation curves are compared with those obtained, for the same sample, in standard temperature stimulated non linear dielectric relaxation measurements.