Linear and Nonlinear Optical Properties of Silver-Coated Gold Nanorods

Abstract

Silver-coated gold nanorods (GNRs) with large longitudinal surface plasmon resonance (SPR) wavelength tunability were fabricated by depositing silver (Ag) on the surface of GNRs. Linear and third-order optical nonlinear properties together with the ultrafast response time of these nanorods were investigated. The results demonstrate that the longitudinal SPR wavelength of GNRs is very sensitive to the thickness (<i>t</i>_Ag) of the Ag coating layer, which changes the dielectric constant of the environment. As <i>t</i>_Ag increases from 0 to 15 nm, the SPR wavelength decreases dramatically from 840 to 520 nm, the corresponding wavelength-dependent third-order optical susceptibility changes dependently with the changing of the SPR absorption curve while the one-photon and two-photon figures of merit were required for optical switching applications, and the ultrafast response time also changes continuously with varying SPR wavelength. These observations are important for applications of plasmonic structures in ultrafast wavelength division multiplexing devices