LAUSR

Abstract In this paper, the third-order nonlinear optical properties of nickel immobilized on acid-activated montmorillonite (MMT@Ni) and copper ferrite (CuFe2O4@Ni) nanocomposites were investigated. The mentioned nanomaterials were synthesized and then characterized using FT-IR, SEM, EDX, XRD, VSM, and TEM analyses. The nonlinear absorption and refractive coefficients of these nickel nanocomposites were measured by Z-scan technique through a continuous wave diode-pumped laser at 532 nm wavelength. The values of nonlinear absorption and refractive indexes of samples were obtained in order of 10− 4m/w and 10− 10m2/w, respectively. In addition, the sign of nonlinear refractive index for MMT@Ni and CuFe2O4@Ni was shown to be positive and negative, respectively. It seems that the difference in activities of nanocomposites was relevance to their structural frameworks. Nickel immobilized on acid-activated montmorillonite has layered structure and this provides the possibility to focus the laser beams, and so self-focusing phenomenon was happened. Whereas, nickel immobilized on copper ferrite has inverse spinel structure and this provides the possibility to diverge the laser beams, and so self-defocusing phenomenon was taken place. The results also showed that the values of nonlinearity for solution of CuFe2O4@Ni and MMT@Ni nanoparticles were respectively increased and decreased by rising of the input intensity. In addition, we found that the support of nickel nanoparticles could change the sign of nonlinear optical behavior.