Third-order nonlinear optical properties of poly(1,4-vinylenephenylene) and its derivatives

Poly(1,4-phenylenevinylene) (PPV) and its derivatives are readily processable and thermally stable polyconjugated polymers. Since PPV contains phenylene units, its structure can be easily altered and modified in the electronic structure. Moreover, PPV and the derivatives are easily prepared via water-soluble or organic-soluble precursor polymers. Various PPVs substituted with electron-donating or -withdrawing groups were synthesized and their third-order optical nonlinearities were investigated by third-harmonic generation method or degenerate four-wave mixing technique. When phenylene rings carry two alkoxy electron-donating groups, the substituted PPVs show third-order nonlinear chi((3)) value of about 10(-9) esu. In order to obtain polymeric materials having high optical quality, PPV and silica alkoxide can be mixed successfully by sol-gel processing without any phase separation or precipitation. This unusual organic-inorganic hybrid shows a great advantage in the photonics applications.