Topology induced anomalous plasmon modes in metallic Mobius nanorings

TL;DR

This paper explores how the topology of metallic M"obius nanorings induces unique anomalous plasmon modes, enabling high-sensitivity sensing and novel plasmonic phenomena due to their non-orientable surface and half-integer mode resonances.

Contribution

It demonstrates the existence of topology-induced anomalous plasmon modes in M"obius nanorings, revealing their invariant resonant properties and potential for enhanced plasmonic applications.

Findings

Half-integer resonant modes due to topology

Bright modes enabled by symmetry breaking

High sensitivity in plasmonic sensing

Abstract

We report on the investigation of plasmonic resonances in metallic M\"obius nanorings. Half-integer numbers of resonant modes are observed due to the presence of an extra phase {\pi} provided by the topology of the M\"obius nanostrip. Anomalous plasmon modes located at the non-orientable surface of the M\"obius nanoring break the symmetry that exist in conventional ring cavities, thus enable far-field excitation and emission as bright modes. The far-field resonant wavelength as well as the feature of half-integer mode numbers is invariant to the change of charge distribution on the M\"obius nanoring due to the nontrivial topology. Owing to the ultra-small mode volume induced by the remaining dark feature, an extremely high sensitivity as well as a remarkable figure of merit is obtained in sensing performance. The topological metallic nanostructure provides a novel platform for the investigation of localized surface plasmon modes exhibiting unique phenomena in plasmonic applications such as high sensitive detection and plasmonic nanolasers.