Two Photon Absorption spectroscopy of polyDCHD-HS

We report here the two-photon absorption spectrum of thin films of poly-[1,6-bis(3,6-dihexadecyl-N-carbazolyl)-2,4-hexadiyne]diacetylene (polyDCHD-HS) recorded through nonlinear transmission measurements performed in the near infrared (900-1550 nm) with femtosecond pulses. A simple three level model of the third order susceptibility well accounts for the Two Photon Absorption and it is used to predict the nonlinear refraction. At 1550 nm, where TPA was found to be very small-if-any, the real part of the susceptibility is of the oreder of 10-19 m2/V2, one of the highest values so far prospected