Measurement of the two-photon absorption cross sections of dicyanomethylene-pyrans by the z-scan method

The two-photon absorption cross sections of three dicyanomethylene-pyrane DCM dyes excited by a femtosecond pulsed from a Ti:sapphire laser are measured by the open-aperture z-scan method. The experimental transmission curves are approximated by the corresponding model curves to give the two-photon absorption cross sections equal to 5.1 $\times10^3$ GM, 5.7 $\times10^3$ GM, and 8.4 $\times10^3$ GM for DCM, DCM-17, and DCM-doa, respectively (1 GM $=10^{-50}$ cm$^4$s phot$^{-1}$ mol$^{-1}$).