High Temperature Nonlinear Optical Chromophores and Polymers.

Abstract : We have developed a thermal protocol for the evaluation of NLO chromophores for very high temperature electro-optical applications with poled polymers. This protocol has been demonstrated to have significant predictive utility for EO applications. We have demonstrated that while chromophore thermal instability and nonlinearity are linked, this relationship is not inviolable. Certain thermally stable NLO chromophores have been incorporated into polyimide derivatives either by flexible tether connections or by direct embedding of the donor portion into the polymer main chain. In each case, orientational stabilities for over 1000 hours at 100 C were achieved, so long as the Tg of the polymer exceeded 200 C. The embedding of the chromophore into the main chain gave polymers with exceptional thermal and oxidative stability and polymer Tg values which ranged from 250 - 350 C. Orientational stability of the embedded donor, poled polymers was outstanding and exceeded any reported in the literature, including those examples which had been stabilized by extensive crosslinking. Preliminary results on the low temperature poling of high Tg azo containing polymers by irradiation with polarized light in the presence of an electric field were encouraging as an alternative to thermal poling.