Removing a Wedge from a Metallic Nanodisk Reveals a Fano Resonance

A wide variety of complex, multicomponent plasmonic nanostructures have been shown to possess Fano resonances. Here we introduce a remarkably simple planar nanostructure, a single metallic nanodisk with a missing wedge-shaped slice, that also supports a Fano resonance. In this geometry, the Fano line shape arises from the coupling between a hybridized plasmon resonance of the disk and a narrower quadrupolar mode supported by the edge of the missing wedge slice. As a consequence, both disk size and wedge angle control the properties of the resonance. A semianalytical description of plasmon hybridization proves useful for analyzing the resulting line shape.