Ultrahigh Q-factor and figure of merit Fano metamaterial based on dark ring magnetic mode

A planar terahertz (THz) metamaterial with both ultrahigh quality (Q) factor and high figure of merit (FOM) based on the ring magnetic mode and Fano resonance is proposed. The nonradiative dark modes are induced by the tiny symmetry breaking of the symmetrical split resonance rings (sSRR) under the normal illumination of THz waves with both electric and magnetic components lay in the structure plane. The samples are fabricated and measured with a conventional THz time-domain spectroscopy. Such a sharp and pronounced resonance can benefit the applications such as biosensor, narrowband filter, and laser sparser.