Third order nonlinear susceptibility of Cu nanoparticles, Ag nano-wires, and their mixture at different wavelengths

Abstract

In this paper, the nonlinear refraction and third-order nonlinear optical susceptibility of suspended Cu nanoparticles, Ag Nano-wires (Diameter:200 nm and Length: (5-50) nm) and their 1:1 mixture have been studied by using different laser wavelengths. The nonlinearity of these suspensions has been examined by z-scan technique. The adhesion of the Cu nanoparticles (NP) on the Ag Nano-wires (NW) has been confirmed by SEM characterization. The linear absorption spectra of the Cu NPs and the mixture show broadband absorption over the entire visible band. The results show that all suspensions have negative nonlinear refractive indices at all the used wavelengths with relatively significant values. The results show that nonlinear refractive index has maximum absolute values (17.22×10−11, 8.83×10−11 and 11.8×10−11) m2/W and third-order nonlinear optical susceptibilities (31.3×10−5, 35.8×10−5 and 22.9×10−5 (esu)) for Cu NP, Ag NW and the mixture respectively at (405 nm). The nonlinear refractive index has minimum absolute values (2.74×10−11, 1.09×10−11 and 2.34×10−11) m2/W and third-order nonlinear optical susceptibilities (5.15×10−5, 3.35×10−5 and 4.3×10−5 (esu)) for Cu NP, Ag NW at (532 nm). The addition of Cu NPs to Ag NW enhances the nonlinearity of the Ag NW and flattens the linear absorption of the mixture.