Third-order optical nonlinearity of multi-armed CdS nanorods measured by the Z-scan method

The multi-armed CdS nanorods were synthesized by aqueous chemical growth route at room temperature. The nonlinear optical properties of CdS nanorods dispersed in ethanol solution were investigated using the Z-scan method at a wavelength of 532 nm with pulse duration of 25 ps. The third-order nonlinear optical susceptibility, χ(3), was determined to be 1.6×10−13 esu. Accounting for the CdS concentration and the effect of the dielectric confinement, χ(3) was extrapolated to be ∼10−9 esu, which is over one order of magnitude larger than that of bulk material.