Third harmonic autocorrelation and wave mixing in a thin film of poly(p-phenylenevinylene)

We show here that a thin film of a nonlinear conjugated polymer: poly(p-phenylenevinylene) (PPV) is capable of efficiently generating the third harmonic of femtosecond pulses of light at the near infrared (including telecommunication bands) wavelengths, giving coherent, low divergence beams in the visible range. By using more than one fundamental beam overlapping in space and in time on the PPV film, autocorrelation signals are observed as well as higher order mixing signals due to χ⁽⁵⁾ and higher-order nonlinear susceptibilities. These signals can be used for applications such as short laser pulse diagnostics and photonic signal processing and they provide information about the nonlinear properties of the material itself.