Numerical investigation of coupling efficiency between a magnetic line dipole emitter and surface plasmon polariton modes of a nanometer thin metallic film

Abstract

In this paper we considered a line magnetic dipole emitter near a 25nm thick silver film embedded in a homogeneous dielectric environment. By using a two dimensional magnetic Green's function, the Purcell factor and coupling efficiency factor (β factor) for symmetric and antisymmetric surface plasmon polaritons (SPP) and out of plane (OUP) propagating decay channels were calculated. For a fixed wavelength emission, the effects of source position and refractive index of the dielectric medium on the Purcell factor and β factors are investigated.The numerical results show that, where the Purcell factor is maximum (minimum) the antisymmetric (symmetric) SPP is dominant decay channel and the selective excitation of symmetric SPP is better achievable in the case in which the dielectric medium has the higher refractive index. The wavelength dependency of β factors is also investigated for different source locations. This investigation shows that how the wavelength position for the peak of β factors depends on source location. The results of this paper could have implications for metamaterials research and many lanthanides based photonic devices.