Plasmon resonances in a quartz nanofilament covered with gold of variable thickness

Abstract

A two dimensional problem of diffraction of a plane electromagnetic wave by a cylindrical gold shell is considered in the case when the boundaries of the shell are circular cylinders with displaced centers. The influence of the excentricity of the boundaries on the properties of plasmon resonances in the optical band is studied. The near and far fields and scattering spectra are calculated by rigorous methods. It is found that the excentricity of shell’s boundaries gives rise to additional resonances. Analytical theory of scattering for thin shells is developed in the quasi-static approximation. It is shown that, in this case, the scattering and absorption spectra essentially depend on the displacement of the centers of the cylindrical boundaries but are independent of the direction of this displacement.