Electromagnetic Responses and Coupling Effect in Asymmetric Terahertz Metamaterials

Abstract

We experimentally and numerically demonstrate resonant behaviors of terahertz metamaterials can be tuned significantly by their asymmetry. In the asymmetric U-shaped structure, when terahertz electric-field is perpendicular to bottom bar, an interesting phenomenon comes up with three dips, which differs from the split-ring resonator which only has one dip in the transmission spectrum. By altering the position of the intermediate wire added in the asymmetric U-shaped structure, we could achieve and modulate resonant behaviors of the asymmetric samples, showing strong dependence on the polarization of the terahertz E-field. For the asymmetrically-cut double-ring structures, the mutual coupling between four arcs results in multi-resonance dips, especially a low-frequency Fano-like resonance accompanied with a sharp peak. Our asymmetric structures could offer potential applications in terahertz frequency selectors and bio-sensors.