Plasmon Resonances in a Glass Nanowire Covered with a Silver Layer of Variable Thickness

Abstract

A two-dimensional problem of diffraction of a plane electromagnetic wave by a silver shell with the boundaries formed by a circular and an elliptical cylinders is considered. The far fields and the scattering spectra are calculated by rigorous methods in the visible band. The dipole and quadrupole resonance frequencies for thin shells are determined in the quasi-static approximation. It is shown that the quadrupole resonances are degenerate and the dipole resonances are “split”; at the dip frequency, the scattered field can be directed perpendicularly to the direction of propagation of the incident plane wave.