Local Field Enhancement of Pillar Nanosurfaces for SERS

We present studies on the analysis and characterization of a unique nanosurface used for Surface-Enhanced Raman Spectroscopy. The optical properties of a nanostructure composed of dielectric pillars that support plasmonic nanoparticles have been investigated. A theoretical analysis has been performed to determine the structural properties that localize the electric field around the silver disk. We define an enhancement factor in terms of the local field integrated over the nanoparticle surface and find that this figure of merit varies considerably depending upon the pillar attributes. An analytic model is presented and validated via full wave analysis, which elucidates the optical effects occurring in the nanostructure. Starting from the basic phenomenology associated with a single pillar structure, we show that several different effects combine to create a global resonance.