Topology induced anomalous plasmon modes in metallic Möbius nanorings

• Published in: Laser & photonics reviews 2017-03, Vol.11 (2), p.np-n/a
• Main Authors: Yin, Yin, Li, Shilong, Engemaier, Vivienne, Saei Ghareh Naz, Ehsan, Giudicatti, Silvia, Ma, Libo, Schmidt, Oliver G.
• Format: Article
• Language: English
• Subjects: bright plasmon mode; Charge distribution; Constants; dark plasmon mode; half‐integer mode number; Möbius ring; Nanostructure; Photonics; Plasmonics; Plasmons; Symmetry; Topology
• ISSN: 1863-8880; 1863-8899
• DOI: 10.1002/lpor.201600219

We report on the theoretical investigation of plasmonic resonances in metallic Möbius nanorings. Half‐integer numbers of resonant modes are observed due to the presence of an extra phase π provided by the topology of the Möbius nanostrip. Anomalous plasmon modes located at the non‐orientable surface of the Möbius 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 constant to the change of charge distribution on the Möbius nanoring due to the topology of Möbius ring. 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 our numerical calculations for sensing performance. The topological metallic nanostructure provides a novel platform for the investigation of localized surface plasmon modes exhibiting unique phenomena for potential plasmonic applications. In conventional metal nanostructures, plasmonic resonances are known to be determined by the structure size, geometry, and symmetry. This work reports topology induced anomalous plasmon modes in metallic Möbius nanorings. Half‐integer plasmon modes were observed in the Möbius rings, which cannot exist in conventional plasmonic rings. In addition, the higher‐order plasmon modes turn out to be bright in the Möbius nanorings, while they are supposed to be dark in conventional plasmonic‐rings.