| Abstract
| - Polyamides based on2‘,5‘-diamino-4-(dimethylamino)-4‘-nitrostilbene (DDANS) andlinearaliphatic diacids represent a class of polymers with large and stablesecond-order nonlinear opticalproperties, where the nonlinear optical units are fixed in the polymerbackbone with their dipole momentsoriented transversely to the main chain. Such NLO polymers wereprocessed by spin-coating into planarwaveguides ranging from 500 to 1500 nm in thickness. Subsequently,a macroscopic noncentrosymmetricorientation of the NLO-phores was induced by a corona-discharge polingprocess. The refractive indices,nTM and nTE, and theelectro-optic coefficients, r33 andr13, were determined by measurement ofthewaveguiding modes of such devices at a wavelength of 785 nm. Theelectro-optic coefficient r33 of 12pm/V compares favorably with state-of-the-art polymeric electro-opticmaterials. It also equals approximately the electronic contribution to the electro-optic effectwhich can be calculated from the nonlinearoptical susceptibility d33. The ratio ofelectro-optic coefficientsr33/r31 was found to be≈3, independent ofthe magnitude of the NLO-phore orientation. This behavior is inperfect agreement with the predictionsfrom the isotropic model.
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