High-Order Surface Plasmonic Resonance and Near Field Enhancement in Asymmetric Nanoring/Ellipsoid Dimers

Optical properties of the asymmetric nanoring/ellipsoid dimers with breaking of geometric symmetry are investigated theoretically. A tunable high-order surface plasmonic resonance is achieved. It is demonstrated that such high-order resonances result from the plasmonic coupling between the modes of a nanoellipsoid and of an asymmetric nanoring. Interestingly, a current loop is observed on the nanoellipsoid under coupling of the two nanostructures. The surface plasmonic resonance of this nanostructure can also produce enhanced local fields that can be applied in surface-enhanced spectroscopy and biosensing.