Asymmetrically engineered metallic nanodisk clusters for plasmonic Fano resonance generation

In this paper, we numerically introduce a planar metamolecule that generates plasmonic Fano resonance. The engineered molecule consists of closely packed asymmetric gold nanodisks deposited on a glass substrate operating at visible and near-infrared wavelengths. The asymmetric arrangement of nanodisks plays a key role in Fano resonance generation. The induced extinction cross-section spectroscopy has a Fano-like shape owing to interference between bright and dark plasmonic modes sustained by the asymmetric nanodisk clusters. The Fano dips are shown to be highly sensitive to the interdisk gaps as well as to the surrounding environment. As a result, we introduce a potential refractive index nanosensor having a sensitivity of 660 nm/RIU and a figure of merit of 4.75. The proposed metamolecule holds potential for various applications, such as Fano-induced enhancement of solar energy harvesting, molecular fluorescence, and photo upconversion.