A molecular plasmonic Fano-router: Using hotspots in a single-stone ring-like structure

In the past decade there has been outstanding, continuing interest in developing novel structures to engineer and control light-matter interactions in subwavelength dimensions with desired optical characteristics. Herein, we propose a unique plasmonic configuration consisting of a split-ring and a nanosphere in the split section (resembles a single-stone ring). We show that this simple and antisymmetric structure is able to support pronounced antisymmetric Fano resonance at the near-infrared region, while strong hotspots form at the gap space between the split-ring terminals and the nanosphere. The antisymmetric feature of the structure facilitates strong-dependency on the polarization of the incident beam. Having strong sensitivity to the incident polarization angle, we tailored a fast plasmonic Fano-router based on the behavior of Fano resonant mode. This study could help realizing Fano resonance based photonic devices using simple and antisymmetric nanostructures.