Abstract
We study the properties of plasmonic excitations localized at 2D and 3D nanoscale perturbations of a flat metal surface within the general method of surface integral equations. The resonant values of the optical permittivity and the plasmonic eigenfunctions—distributions of the surface charge density —are investigated. General symmetry properties linking the cases of convex and concave perturbations (bumps and mirror-reflected pits) are established. The impact of the height-to-width perturbation ratio on the localized surface plasmons is twofold: while the resonant permittivities drop linearly with leading to strong redshifts of the resonances, the scale of localization stays constant (). The presence of sharp shape features (tips and corners) with the curvature radius leads to superlocalization of charge density on the scale of and, simultaneously, to an additional strong drop of .
© 2014 Optical Society of America
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