Surface Plasmons and Singularities

We apply the conformal transformation technique to study systematically a variety of singular plasmonic structures, including two-dimensional sharp edges, rough surfaces, and nanocrescents These structures are shown to exhibit two distinct features First, different from a planar metallic surface, the surface plasmon excitations on the examined structures have a lower bound cutoff at a finite frequency. second, the electric field diverges below a critical frequency even when metallic losses are considered For rough surfaces and open-crescent nanostructures. the influence of the structure shapes on the absorbance characteristics is also discussed Our analysis gives a unique insight into the light capture process on singular structures and holds the promise of detection of single molecules and greatly enhanced nonlinear effects