首页|Plasmonic excitations in nanorings: Thickness dependent unusual coupling effects
Plasmonic excitations in nanorings: Thickness dependent unusual coupling effects
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NSTL
Elsevier
Plasmonic coupling in both metallic and graphene nanostructures, is of particular interest for fundamental physics and potential applications. Here, we study plasmonic coupling in gold nanorings possessing different vertical thickness, by using three-dimensional finite element method as implemented in COMSOL MULTIPHYSICS. As well known, the coupling between inner and outer edges will result in mode splitting, namely, a symmetric (lower frequency) mode and an antisymmetric (higher frequency) mode; and a larger coupling corresponds to a larger mode shifting, e.g. with a blueshift for the antisymmetric mode and a redshift for the symmetric mode. However, in very thin gold nanorings, we find as increasing the ratio of inner radius to outer radius (equivalently increasing the coupling), the antisymmetric mode exhibits a redshift at first and then a blueshift, which is consistent with that in graphene nanorings of zero thickness. We show this unusual coupling effect depends on the thickness and size of nanorings, and is more significant in nanorings of smaller thickness and size. Our work is a nature extension of recent plasmonic studies, and offers an alternative way to tune in-plane plasmonic resonances by the vertical dimension.
NSTL
Elsevier
