ELECTROOPTICS IN THERMOPOLED POLYMER-FILMS

We present a range of measurements on the electro-optic (e-o) properties of polar polymeric films. The polar order is induced via thermopoling using fixed contacts. In doped films, high doping concentrations (20% wt) have been achieved of the non-linear organic molecule 2-(N,N-dimethylamino)-5-nitroacetanilide, DAN. The e-o coefficients obtained include a contribution from the host polymer in the case of a polycarbonate host where films have e-o coefficients higher than those of comparably doped PMMA materials. Among 'side-chain' polymers we find that poly(4-vinylpyridine), P-4VP, obtained commercially, also can be poled efficiently and yields moderate e-o coefficients. An experimental value for the microscopic nonlinear figure of merit mubeta in P-4VP is calculated and compared with a theoretical value. The resulting mismatch reveals that the simplified thermodynamic model may be inappropriate for this side chain polymer and that low-frequency contributions to the nonlinearity may be significant.