Improved attenuated-total-reflection technique for measuring the electro-optic coefficients of nonlinear optical polymers

Anew technique for measuring the electro-optic coefficient of nonlinear optical polymer is described. In an attenuated-total-reflection experiment the refractive index of the poled polymer is changed because of the Pockels effect. This change causes a shift of the angular position of the surface plasmon modes that corresponds to a change in reflectivity at a fixed angle. By measuring the change of the light reflectivity at the properly chosen angle one can calculate the electro-optic coefficient of the poled polymer. Compared with other, conventional methods, here the electro-optic coefficients are given in a simpler form and the required parameters are easier to measure. The commonly used lock-in amplifier is not required. This technique is a highly sensitive method for measuring the electro-optic coefficient because of the newly chosen working interior angle for which a tiny change in the refractive index leads to a large change in reflectivity. (C) 2000 Optical Society of America [S0740-3224(00)00505-1]. OCIS codes: 240.6680, 250.2080, 310.6860.