ELECTROOPTIC COEFFICIENTS IN ELECTRIC-FIELD-POLED POLYMER WAVE-GUIDES

Planar waveguides were made from a linear epoxy copolymer of bisphenol-A diglycidyl ether and amino-nitrotolane. The refractive indices, n(TM) and n(TE), and the electro-optic coefficients, r33 and r13, of the poled nonlinear-optical polymer films were determined by measurements of the waveguide modes of these films at a wavelength of 632.8 nm, and the results are reported for both electrode and corona poling. The ratio of the second-order susceptibilities was found to exceed significantly the theoretically expected value of 3. The restricted motion of the nonlinear chromophores during poling provides a possible explanation of this discrepancy. Introducing a restriction parameter-nu (0 less-than-or-equal-to nu less-than-or-equal-to 1), we develop a simple model that can account for electro-optic coefficient ratios ranging from 3 to 6.