Electric Field Effects in Poled Polymer Thin Films

Abstract

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).