Mie plasmons: Modes volumes, quality factors, and coupling strengths (Purcell factor) to a dipolar emitter

Abstract

Using either quasistatic approximation or exact Mie expansion, we characterize the localized surface plasmons supported by a metallic spherical nanoparticle. We estimate the quality factor Q n and define the effective volume V n of the n th mode in such a way that coupling strength with a neighbouring dipolar emitter is proportional to the ratio Q n / V n (Purcell factor). The role of Joule losses, far-field scattering, and mode confinement in the coupling mechanism is introduced and discussed with simple physical understanding, with particular attention paid to energy conservation. Copyright © 2012 G. Colas des Francs et al.