QUADRATIC ELECTROOPTIC EFFECT IN MOLECULES WITH LARGE OPTICAL HYPERPOLARIZABILITIES

We report quadratic electrooptic derived third-order optical polarizab ilities, gamma, on two thiazole azo dyes that we have previously demon strated to possess large optical hyperpolarizabilities, beta. We demon strate that the data are consistent with our previously introduced res tricted three-level model for gamma. Specifically we show that the sus ceptibility can be accounted for by two perturbative terms and that we are also possibly observing the predicted enhancement in gamma for mo lecules with large beta when the peak narrows. We also suggest that th is mechanism offers an approach to systematic improvements for the rat io Re[gamma]/Im[alpha].