Relaxation and optical attenuation characteristics of poled second-order nonlinear optical polymers: influence of chromophore concentration and high-field poling

Summary form only given. Second-order nonlinear optical (NLO) polymeric systems, based on two NLO chromophores (Disperse Red l and p-nitroaminotolane) attached to poly(methyl methacrylate) as pendant substituents, were investigated concerning their NLO, relaxation and optical attenuation properties as a function of chromophore concentration. The NLO decay characteristics measured at 80/spl deg/C, below the glass transition temperatures of polymers, show that the decay rate decreases substantially with increasing NLO chromophore concentration, although the glass transition temperatures of the polymers are practically the same, ca. 120/spl deg/C. This chromophore concentration dependence appears to be related to the varying breadth of the high temperature /spl alpha/-relaxation process, separately investigated by dielectric spectroscopy. Optical waveguide measurements show that high-field poling results in greater optical attenuation that increases with increasing chromophore concentration. This poling-induced optical attenuation seems to arise from the aligned chromophores, since the NLO decay below the glass transition is accompanied by a mostly reversible reduction in optical attenuation. Therefore, the interactions among the NLO chromophores are found to play important roles in determining the NLO stability and optical attenuation characteristics of poled amorphous second-order NLO polymers.