Nonlinear optical properties of a dithiooxamide determined by single beam techniques

The third-order nonlinear optical properties of an inorganic compound (NH2CSCSNH2) were studied by means of single beam transmission techniques, using a continuous-wave (CW) He–Ne laser beam with a wavelength of 632.8 nm a laser power of input 6.6 mW. The magnitude and sign of the third-order nonlinear refractive index (n2) of a saturated solution of this material in water were determined by use of both the closed-aperture z-scan and the Moiré deflectometry techniques. The negative sign obtained indicated that there is a self-defocusing effect in the sample. The nonlinear refractive index n2 and the change in the refractive index (Δn) were in the order of 10−7 cm2 W−1 and 10−5, respectively, both having a negative sign. The nonlinear absorption coefficient β was calculated by the use of the open-aperture z-scan technique to be −1.8 × 10−3 cm W−1.