Directional light emission by electric and magnetic dipoles near a nanosphere: an analytical approach based on the generalized Mie theory.

Abstract

We present a theoretical study of directional light emission by dipole emitters near a spherical nanoparticle. Our analysis is extended from an exact electrodynamical approach for solving the coupling between a dipole and a sphere, providing a full picture of the directional emission for a complete set of combinations of variable emitters, particles, and their orientations. In particular, we show that the Mie resonances of a dielectric sphere are strongly influenced by the coupled dipole emitter, leading to the scattering properties that are different from the prediction by the standard Mie theory. Moreover, we demonstrate that the dielectric spheres have opposite effects on the emission direction and a decay rate of electric and magnetic dipoles. Our approach enriches the analytical toolbox for designing optical antennas and understanding dipole-sphere coupling.