Simulation of metallic nanoparticles situated on substrates using the boundary element method
Jürgen Waxenegger
University of Graz
14:00 - 14:40 Friday 26 June 2015 HS 05.12 Physikgebaeude, Universitätsplatz 5

Metal nanoparticles sustain local surface plasmon excitations, particle plasmons, which are hybrid modes of a light field coupled to a coherent electron charge oscillation. Understanding the optical response of metal nanoparticles is important to fully exploit their unique properties for nanoscale light concentration. In recent years computer simulations have become indispensible in this research field. One computational scheme, well suited for such plasmonic simulations, is the potential-based boundary element method (BEM). However, it has been unclear whether and how substrate and layer effects can be included in this approach.

In this talk we present a methodology of simulating plasmonic nanoparticles within the inhomgenous dielectric environment of a layer structure using BEM, and demonstrate its applicabilty. With this modification BEM simulations of nanoparticle samples fabricated with electron beam lithography become feasible.

We show how to derive the BEM equations for layer structures and how to calculate the reflected Greens functions, which are essential ingredients of this new BEM approach, by using Sommerfeld integrals. A significant speed up is achieved by computing the reflected Greens functions on a suitable grid and interpolating them at later stage. We perform simulations for different structures and finally compare results of the boundary element method implementation with results obtained with discrete dipole approximation simulations including substrate effects, finding good agreement throughout the entire wavelength regime.