Super-radiating manipulation of a nano-emitter by active toroidal metamaterials

Jie Li,Jia-Qi Li,Ying-Hua Wang,Ming-Jie Zhu,Ren-Chao Jin,Zheng-Gao Dong

doi:10.1038/srep46609

Abstract

The far-field radiation of a single dipolar emitter can be controlled by coupling to toroidal dipole resonance attached to metallic double flat rings, realizing a conversion from non- to super-radiating. The underlying physical mechanism is the hybridization interference of toroidal and electric dipoles under an asymmetric configuration by introducing a radial displacement of the dipolar emitter. By embedding gain medium in the gap spacer between double flat rings, the directional far-field super-radiating power can achieve a tremendous enhancement with a moderate requirement on the gain coefficient, promoting light-matter interaction manipulation.

Highlights

As one member of the third family in electromagnetic multipole theory[1,2], toroidal dipole was proposed by Zel’dovich in 1957 to interpret the parity violation on the weak interaction in nuclear and particle physics[3], which is a result of current flowing on the surface of a torus along its meridian[4,5]
In our previous work, a dipolar emitter coupling to the metastructure by double flat rings excites toroidal dipole and controls both radiating direction and power of the dipolar emitter by tuning geometric parameters, acting like a nanoantenna[13]
We embed the gain medium into the gap spacer between metallic double flat rings to explore the influence of optical gain on the far-field scattering properties based on the coupling interference between toroidal and electric dipole radiations

Summary

Introduction

As one member of the third family in electromagnetic multipole theory[1,2], toroidal dipole was proposed by Zel’dovich in 1957 to interpret the parity violation on the weak interaction in nuclear and particle physics[3], which is a result of current flowing on the surface of a torus along its meridian[4,5]. We embed the gain medium into the gap spacer between metallic double flat rings to explore the influence of optical gain on the far-field scattering properties based on the coupling interference between toroidal and electric dipole radiations.

Results

Conclusion