Fano resonance in dual-disk ring plasmonic nanostructures.

A dual-disk ring (DDR) structure with broken symmetry and weakly dissipating material, silver, is proposed to achieve Fano resonance in visible wavelength range. Symmetry breaking of a metallic ring is realized by placing two disks inside the ring. The excitation of the Fano resonance is interpreted in terms of coupling of the ring and the dual-disk plasmonic modes. The potential of using an array of such DDR nano structures as a biochemical sensor is evaluated with the figure of merit (FOM). Based on our design and simulation, arrays with DDR structures are fabricated and the Fano resonance peak is observed in visible wavelength range of extinction spectra of individual silver DDR nanostructures.