Third-Order Optical Nonlinearity of Au-Ag core-Shell Nanoparticle at 532 nm

Au-Ag core-shell nanoparticles in aqueous solution for the various molar ratio of Au and Ag has been synthesized using simple chemical reduction method. The TEM image of the Au-Ag nanoparticles sample gives the confirmation of core-shell structure. The average particle size of Au-Ag core-shell is 10 nm. The Au-Ag colloidal core-shell nanoparticle samples characterized by UV-VIS absorbance and Z-scan technique. The nonlinear refractive index (n2), the nonlinear absorption coefficient (), and third order susceptibility (3) have calculated for an increase in molar ratio of Au and Ag. The results show that concentration of the reactants can directly affect and alter the nonlinear parameters. As a photonics application is a concern, Au-Ag core-shell nanoparticles optical limiting behavior is also observed. As expected, the sample which has higher nonlinearity shows quickly saturated for input intensity.