Dipole emission characteristics near a topological insulator sphere coated with a metallic nanoshell

Abstract

The modified emission characteristics of a source dipole near a metal-coated topological insulator sphere are studied with the application of axion electrodynamics in the long wavelength limit. Our focus is on the effect due to the topological magneto-electric (TME) response of the sphere and its influence on the multipolar plasmonic resonance of the metallic nanoshell. It is found that the TME response mainly affects the bonding modes of the metal shell plasmons with the lower order multipole resonances experiencing appreciable red-shifts. In addition, the TME effects can lead to either greater or smaller decay rates and lower emission frequencies, depending crucially on the frequency of the emitting dipole; but otherwise rather insensitive to the orientation of the dipole moments. These findings thus provide an alternative approach to probing the TME effects via molecular fluorescence experiments, as well as new possibility of controlling the emission properties of molecules using these novel nanoparticles.