Defect-Induced Fano Resonances in Corrugated Plasmonic Metamaterials

A novel defect-induced planar meta-atom that supports multiple Fano resonances in a defective corrugated metallic disk (CMD) structure is proposed. Numerical and experimental results reveal that multiple Fano resonances can be excited at terahertz frequencies when the symmetry of the CMD is broken by introducing a small angular defect. These multiple Fano resonances result from mutual coupling between the bright dipolar mode evoked by the edge of the wedge-shaped slice and dark multipole spoof localized surface plasmon modes. Furthermore, the influence of the angle of defect on the Q-factor and the resonance intensity of the quadrupolar resonance peak is investigated. Large values of figure of merit are obtained due to higher Fano resonance intensity and Q-factor. Results from two defective slices in the CMD structure validate the mechanism of the observed phenomenon. The findings of this work would enable a defect-induced Fano resonance platform for biosensing, terahertz domain filtering, and strong light-matter interactions.