Nonlinear optical response of gold nanospheres immobilized on gold surface and its application to biosensing

Abstract

Metallic nanostructures, such as gold nanospheres, show characteristic optical properties that differ from those of the bulk, due to localized surface plasmon (LSP) resonance. LSPs provide us with a large enhancement of the electric field of incident light, and the multiphoton processes, such as Raman scattering and nonlinear optical effects, are markedly sensitized by this enhancement of the electric field. We present a new multichannel label-free biosensing method based on LSP-enhanced second-harmonic generation using a gold nanostructure consisting of surface-immobilized gold nanospheres that is optimized for LSP sensing.