Third-order nonlinear optical behaviour of hybrid phenylene-ethynylene phenylene-vinylene polymers

The \n(2)\-values of novel hybrid phenylene-ethynylene/phenylene-vinylene polymers 1, 2, 3, 4, together with those of corresponding pheryleneethynylene 5 and phenylenevinylene 6 and 7 'homopolymers', have been studied by time-resolved degenerate four-wave mixing (DFWM). The measurements were performed on thin films at 800 nm with femtosecond time resolution using a folded boxcars setup. No clear relationship between \n(2)\-values and the backbone conjugation pattern of the compounds could be established. In contrast, a quasi-exponential relationship between film thickness and the \n(2)\-value was observed, irrespective of the chemical structure of the samples.