Much effort has been put into improving the temporal stability of electric field-induced chromophore alignment in molecularly doped or functionalized polymers for second order nonlinear optical device applications. Characterization of the alignment decay in electric field-poled films is complicated by charge injection during poling. In order to optimize poling schemes and to accurately determine the orientational mobility of the chromophores it is necessary to develop methods to measure the spatial extent and time-dependence of any residual fields in the polymer films. Such Measurements will also be important for the development of polymer-based electro-optic devices, and in fact for any guided wave application in these materials since the residual field may induce a spatial dependence in the refractive index.

Polymer thin film systems have been explored as potential materials for nonlinear optical (NLO) device applications using second order nonlinear optical effects such as second harmonic generation and linear electrooptic effect for photonic devices including waveguides and frequency doublers. For second order nonlinear effects to be observed, a noncentrosymmetric orientation of the NLO chromophores, which is obtain by poling with a large magnitude electric field, is necessary. The effects of the electric field during and following poling are poorly understood. During poling, charge is injected into the polymer film affecting the local electric field that the NLO chromophores senses. After poling, these charges that have become trapped in the polymer film system affect the decay of the NLO properties of the film. Therefore, to make efficient nonlinear optical devices, it is necessary to understand the electric field effects on the thermal and temporal stability of chromophore orientation within the polymer thin film system as a function of processing. Electroreflection and dielectric relaxation measurements were performed on poly(methyl methacrylate) doped with 4-dimethylamino-4'-nitrostilbene (DANS).