Nonlinear optical investigations of laser generated gold, silver and gold-silver alloy nanoparticles and optical limiting applications

Abstract

Laser induced synthesis of gold, silver and gold-silver alloy nanoparticles in water and their nonlinear optical investigations are reported. The tunability of localized surface plasmon resonance band of the gold-silver alloy nanoparticles in the wavelength region between gold and silver was established using the UV–Visible absorption studies. The third order nonlinear optical properties like two photon absorption coefficient, optical limiting threshold, non linear refractive index and third order nonlinear optical susceptibility χ(3) of the nanoparticles could be fine tuned by controlling the volume ratios of gold and silver in the gold-silver alloy nanoparticles. The nonlinear optical behavior and optical limiting properties of the gold, silver and gold-silver alloy nanoparticles were found to be considerably affected by the position of inter and intra band absorption wavelength. Dual beam thermal lens method was utilized to determine the variations in photo thermal parameters like thermal diffusivity and thermal lens signal amplitude. The ability to tailor the nonlinear optical characteristics and photo thermal properties of the gold and silver nanoparticles employing the alloy nanoparticles makes them promising candidates in optical limiting, bio photonic, opto-electronic applications.