Engineering of dual-band magnetic dipole decay rate enhancement with concentric hollow nanodisk resonators

Abstract Unlike metal nanoparticles, the dielectric nanoparticles exhibit low-loss electric and magnetic Mie-type resonances. Thus, all-dielectric nanophotonics concept have been considered as the pathway to enable the key applications such as all-photonic quantum information processing. In this context, the efficient decay-rate-enhancement of spontaneous emission have gained interest with the aim of the development of nano light sources. However, due to the neglected interaction of the magnetic component of the light with the matter, the enhancement of the decay rate of the magnetic dipole emission have been ignored. Owing to the capability of efficiently concentrating the magnetic field into subwavelength scale via the Mie-type magnetic resonances, the dielectric nanoparticles such as hollow nanodisks have become intriguing for the magnetic Purcell effect or any optical-magnetism-related application with a demand of magnetic hotspot generation. However, all of the proposed dielectric nanoparticles are designed for single band enhancement which limits the potential of the applications. To overcome this limitation, a novel dielectric resonator architecture based on the nested hollow nanodisks is numerically demonstrated that exhibit dual-band magnetic dipole resonances in the visible and near-infrared range. First the scattering properties of the individual resonators are investigated. Additionally, the near field properties are presented via the field enhancement maps. Finally, the dual-band magnetic dipole decay rate enhancement properties and the dependence on the geometrical parameters are investigated. The results of this study may bring new possibilities to maximize magnetic dipole emission over a wide spectral range that covers visible and near-infrared for the applications such as nano light sources and integrated quantum information technology.