MOLECULAR AND MACROSCOPIC NLO PROPERTIES OF ORGANIC POLYMERS

Two classes of aryltrienes in which the conjugation was incorporated i n six-membered rings have been developed. The microscopic nonlinear su sceptibility, mubeta, the product of the dipole moment and the second- order nonlinear susceptibility, of these chromophores were measured us ing electric field-induced second harmonic generation (EFISH). The chr omophores were then copolymerized as side-chain pendant groups in a me thacrylate backbone copolymer with methyl methacrylate and their macro scopic electrooptic coefficients, r, were experimentally determined us ing a reflection technique after electric field poling of the polymers . When compared with 4,4'-NN-dimethylaminonitrostibene (DANS), these m olecules demonstrated electrooptic activities up to three times of DAN S, when measured at 1.3 mum. By using a simple two-level free-gas mode l, the two sets of measurements corresponded closely at low poling fie lds. At high fields, the simple model breaks down as more detailed pol ing parameters are required to accurately describe the nonlinear polin g effects. The results of the analysis of the high-field poling data w ill be published separately. (C) 1994 John Wiley & Sons, Inc.