A Method for Measuring the Electro-optical Response of Chromofore-embedded Polymer Films Using a Prism Coupler

Abstract

When electro-optical chromophores are embedded into a polymer matrix and aligned in a preferential direction, it becomes possible to control the refraction of light in such a composite medium under the influence of an external electric field. This effect is used in the production of high-speed integrated-optical modulators, switches, etc. We manufactured nonlinear optical polymethyl methacrylate (PMMA) films into which the DR13 chromophore was embedded. An algorithm is created that allows one to determine the electro-optical parameters of films in a multilayer anisotropic structure with metal electrodes, when a control voltage is supplied to them. The electro-optical coefficients r₃₃ and r₁₃ of the PMMA/DR13 composite were found at several wavelengths near the DR13 chromophore absorption peak and far from it. The proposed method makes it possible to measure the electric-field-induced change in the refractive index in the thin-film light-guiding structure of an actual electro-optical modulator with an accuracy of ±0.0005.