Fano-Like Resonances in Asymmetric Homodimer of Gold Elliptical Nanowires

Abstract

The Fano-like resonance properties of the asymmetric dimer for gold nanowires (GNWs) with elliptical section have been investigated based on the 2-D finite element method (2D-FEM). It is found that the reduced symmetry in the GNWs dimer will cause a distinct Fano dip in the absorption spectrum, which arises from the coherent coupling between the superradiant bright mode and the subradiant dark mode. With the increase in the rotation angle of one GNW, the Fano dip in the absorption of the asymmetric dimer enhances first and then reduces. We have further found that the Fano dip in the absorption becomes wider and deeper with the decrease in the separation between two GNWs, whereas the Fano minimum shows a distinct red shift. The tunability in Fano-like resonance of the asymmetric dimer for the GNWs may provide effective applications in sensing and plasmon-induced transparency.