Third-order nonlinear optical properties of bis(tetrabutylammonium)bis(4,5-dithiolato-1,3-dithiole-2-thione)copper

Bis(tetrabutylammonium)bis(4,5-dithiolato-1,3-dithiole-2-thione)copper (BCDT) was synthesized and its third-order optical nonlinearity was characterized using picosecond Z-scan at 1064 nm. The Z-scan spectra reveal a large negative nonlinear refraction coefficient n2 as high as 4.0 × 10−18 m2/W and a slight two-photon absorption β, which is determined to be 3.4 × 10−12 m/W. The molecular second-order hyperpolarizability γ was calculated to be 6.5 × 10−32 esu. All these results suggest that this material has potential for the application of all-optical switching.