Two-photon absorption and optical limiting in tristhiourea cadmium sulphate

A new donor–acceptor type of thiourea metal complex, tristhiourea cadmium sulphate (TTCS) was synthesized through chemical reaction method. Structural and linear optical properties have been measured by XRD, FTIR and UV–Vis techniques. From the XRD analysis, TTCS crystallizes in centrosymmetric space group P 1 ¯ . There is a bathochromic shift in the absorption edge for ethanol compared to water. By the open aperture Z-scan technique (Nd:YAG, 532 nm, 5 ns), the nonlinearity coefficient (β) is measured as 4.1 × 10−11 m/W, which arises from an effective two-photon absorption phenomenon. The resulting optical limiting behavior has a threshold fluence value of 1.5 × 104 J/m2.