Triple-band high Q factor Fano resonances in bilayer THz metamaterials

In this paper, we proposed a bilayer THz metamaterials, which is constructed by two sets of asymmetric split-ring resonators (ASRRs) with different sizes. Simulation results show that three high Q Fano resonances are excited in the bilayer metamaterials at 0.268, 0.418 THz, and 25 at 0.560 THz, and the Q values are 33, 42, and 25, respectively. The field distributions show that resonances at 0.268 and 0.560 THz originate from one of ASRRs, whereas the resonance at 0.418 THz originates from the other set of ASRRs. Further analysis indicates that the three high Q Fano resonances results from a combined action of the in-plane coupling and the interlayer coupling in the metamaterials: the in-plane coupling lead to resonances enhanced and the interlayer coupling lead to the eigenmode of each set of the ASRRs split into two discrete Fano resonances. This triple-band high Q factor Fano resonance metamaterials would open new degrees of freedom for designing advanced chemical and biological sensors and detectors in the terahertz regime.