Metamaterial analogue of electromagnetically induced transparency

In this paper, three types of EIT metamaterials are presented and numerically investigated. The type I metamaterial consists of the SR and the SRR, which are coupled with each other and assigned as the dark resonator and the radiative resonator, respectively. The metamaterial can exhibit EIT effect to both normally and laterally incident electromagnetic waves because of its electric and magnetic response, respectively. The type II magnetic metamaterial consists of the split ring resonator (SRR) and the spiral resonator (SR) along two orthogonal axes. For the excitation with the magnetic field perpendicular to the SRR plane, the SRR and the SR are designated as the radiative element and the dark element, respectively. A transparency window is observed in the overlapped absorption band of the independent resonator because of the destructive interference between the radiative and dark resonators of the metamaterial. The type III metamaterial is consisted of three cut wires of different sizes and parallel to each other. The resonance frequencies are different because the lengths of three metal wires are different. Under the polarization of electrical field, because three cut wires experience strong resonance, two-two overlaps of absorption bands of three cut wires will induce two transparency windows. Numerical simulations are carried out to validate the three types of EIT metamaterials, and the results have proven to be quite effective.