dc and ac Electro-optic response of chromophores in a viscoelastic polymer matrix: analytical model

摘要

We present an analytical model of the influence of a polymer matrix on the electro-optical and second-order nonlinear optical response of polymer films. The interaction between the chromophores and the matrix is characterized by a local molecular field with a randomly varying orientation throughout the polymer volume. The macroscopic properties of the polymer are subsequently obtained by averaging over the fluctuating direction of the field. We consider the influence of the polymer matrix on both static and dynamic properties. In both cases, our results are valid at arbitrarily large field strengths because we avoid resorting to usual expansion techniques. The mathematically demanding ac case is treated in a variational approach, and results for the frequency dependent electro-optic response are presented. The model is found to be in qualitative agreement with the observed temperature dependence of the frequency dependent electro-optic response of a Disperse Red 1/poly(methyl methacrylate) guest/host polymer if an exponentially decreasing molecular field is assumed. (C) 2002 Optical Society of America. [References: 23]