Recent progress in developing highly efficient nonlinear optical chromophores and side-chain dendronized polymers for electro-optics

Recent progress in developing high-performance nonlinear optical chromophores and polymers for electro-optics is reviewed. Using the single-mode focused microwave irradiation, a diversified family of 2,5-dihydrofuran derivatives has been synthesized as a new class of tunable electron acceptors. Very large r₃₃ values (128 and 116 pm/V at 1.3 μm) have been demonstrated by doping one of the 2-dicyanomethylen-3-cyano-4,5,-dimethyl-5-trifluoromethyl-2,5-dihydrofuran (CF₃-TCF)-based chromophores in poly(methyl methacrylate) (PMMA) and a high T_g polyquinoline (PQ-100), respectively. An excellent long-term temporal stability at 85 °C has also been maintained in the PQ system. Two side-chain dendronized NLO polymers have been synthesized. Using a mild, simple, and generally applicable post-functionalization method, highly polarizable chromophores with dendritic modification has been covalently attached to side chains of poly(4-hydroxystyrene). This approach provides the combined advantages of achieving better poling efficiency through the dendritic effect and shortening the development time required for E-O dendrimer synthesis. Systematic property comparison between these polymers and other conventional NLO polymers, such as guest-host and simple side-chain polymers, has been performed. Exceptionally high poling efficiency (a very large E-O coefficient of 97 pm/V at 1.3 μm) and good temporal stability at room temperature were demonstrated in this dendronized side-chain polymer system.