Linear and Nonlinear Optical Phenomena of Metallic Nanoparticles

We have numerically characterized localized surface plasmons (LSPs) of triangular and cubic Ag particles on a substrate using the so-called finite-difference time-domain (FDTD) method. Especially, we have evaluated the effect of roundness around the prism corners on the characteristics of LSPs and, in addition to that, have focused onto a change in the characteristics of LSPs caused by an interaction between a particle and a substrate. Introduction of roundness decreases the field enhancement and existence of the substrate has made characteristics of LSP modes change. We have also simulated nonlinear optical response of an Ag nanosphere coated with a CdS film, being a Kerr material, by using a nonlinear 3-D FDTD method for spherical coordinates. We have presented extinction spectra of a triangle Ag particle that was processed by using a focused ion beam (FIB) lithography. The experimental spectrum has been well interpreted by introducing roundness around the triangle corners. Ag particles coated with a CdS film have been synthesized by employing the reversed micelle method. We have shown the first experimental observation of the optical nonlinear response for the single Ag nanoparticle coated with a CdS material, based on the optical Kerr effect due to an electronic nonlinearity, at room temperature.