Study on the third-order nonlinear optical properties of Cd2+ ion doped ZnS/PVP nanocomposite films

Abstract

Cd2+ ion doped ZnS/PVP nanocomposite films have been prepared using in-situ chemical method. XRD studies confirm the cubic structure of ZnS for all the films. The SEM micrograph shows the mono dispersion of ZnS nanoparticles in PVP matrix. FTIR spectra confirm the formation of nanocomposites containing ZnS nanoparticles and PVP polymer. Optical absorption spectra reveal the blue shift on the absorbance onset with the comparison of bulk ZnS. Photoluminescence spectra show a blue emission peak for all the films. The Z-scan results of all the films show a reverse saturation absorption process in open Z-scan experiment and self-focusing behavior in closed Z-scan experiment. Both ZnS/PVP and Cd2+ ion doped ZnS/PVP films exhibited the large optical nonlinearity and the value of nonlinear refractive index (n2), nonlinear absorption coefficient (β), third-order nonlinear optical susceptibility (χ(3)) and figure of merit (FOM) increase with Cd doping. The estimated n2, β, χ(3) and FOM values are found to be 1.771 × 10−10 m2 W−1, 4.148 × 10−3 mW−1, 1.603 × 10−4 esu and 9.576 × 10−6 esu m 6 mol% Cd doped ZnS/PVP nanocomposite film. The experimental results clearly showed that the Cd2+ ion doped ZnS/PVP nanocomposite film is a worthy candidate for the future nonlinear optical device fabrication.