Optimization of Surface Plasmon Excitation Using Resonant Nanoparticle Arrays above a Silver Film

摘要

A plasmonic coupling device consisting of an array of ellipsoidal silver nanoparticles embedded in silica in close proximity to a silver surface is studied. By tuning the inter-particle spacing, the shape of the particles in the array, and the height of the array above the silver film, the array-mediated surface plasmon excitation is studied. Finite Integration Technique simulations of such a plasmon coupler optimized for operation at a free space wavelength of 676 nm are presented. Plane wave normal incidence excitation of the system results is seen to result in resonantly enhanced fields near the nanoparticles, which in turn excite surface plasmons on the metal film. The existence of an optimum particle-surface separation for maximum surface plasmon excitation efficiency is demonstrated. Analysis of the frequency dependent electric field in the simulation volume as a function of particle aspect ratio reveals the influence of the particle resonance and the surface plasmon resonance on the excitation efficiency.