Increased electro-optic effect in a guest-host electro-optic polymer by adding PEDOT:PSS as an interfacial barrier layer

We used an ellipsometric reflective technique developed by Teng and Man to measure the electrooptic (EO) coefficients of poled thin films in EO multilayer devices with and without a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) conductive barrier layer (CBL). The EO coefficients for the device containing PEDOT:PSS were 260 and 215 pm V−1 at 1.31 and 1.55 m, respectively, which are higher than those for the device without the CBL. Indeed, the highest EO coefficient for the EO polymer poled without TiO2 or the CBL was 166 pm V−1 at 1.55 m, consistent with that obtained for our modulator devices (160 pm V−1). We investigated the electrical properties, surface morphology, and optical quality of a PEDOT:PSS CBL in EO polymer/TiO2 multilayer-slot waveguide modulators. We demonstrated that the PEDOT:PSS functions as an efficient CBL to pole EO polymers in hybrid EO polymer/TiO2 vertical-slot waveguide modulators.