Measurements of the third-order nonlinearity of a soluble polycarbazolyldiacetylene by picosecond Z-scan at 1064 and 1500 nm

The complex χ(3) of toluene solutions of polydiacetylene, polyDCHD-HS, was measured by using Z-scan at λ=1064 and 1500 nm and with picosecond pulses in order to estimate the potentials of this polymer for application to all-optical switching devices. The values of the real part of molecular hyperpolarizability γ were −2.3×10−47 and −3×10−47 m5/V2 at 1064 and 1500 nm, respectively. The nonlinear absorption could be better modeled with a three-photon process at both the wavelengths instead of the expected two-photon mechanism.