Analysis on the origin of the ultrafast optical nonlinearity of carbon disulfide around 800 nm.

The femtosecond open-aperture Z-scan of standard sample CS(2) at 800 and 780 nm is present here by using thinner sample length and an integrating sphere. The open-aperture Z-scan signal is verified to arise mainly from nonlinear scattering, not from two- or three-photon absorption as reported in literature. And the two- and three-photon absorption coefficients of CS(2) are negligible. Therefore, around 800 nm the femtosecond open-aperture Z-scan of CS(2) cannot be used to calibrate Z-scan measurement system, but the closed-aperture Z-scan is capable.