Plasmonic Analog of Electromagnetically Induced Transparency in Stereo Metamaterials

Plasmon-induced transparency (PIT) is a key addition to mimicking the quantum phenomena of electromagnetically induced transparency (EIT) in atomic systems. So far, various metamaterial structures have been proposed to excite and manipulate the PIT effect. However, most of the reported works were based on 2-D metal structures, and consequently, the PIT phenomena often arise from their electric responses. Here, we propose a novel PIT metamaterial scheme based on three vertically placed split ring resonators (SRRs) working at terahertz frequencies. This stereo structure, with a typical EIT-like transmission, couples to both the electric and magnetic fields of the normally incident wave. We numerically demonstrate that the coupling between the radiative and subradiative elements can be modulated not only by their mutual separation but also by the vertical height of the SRRs. In addition, a classical Fano resonance model is applied to explain the coupling effects of EIT-like transmission spectra, which is in good accordance with the numerical results. Considering the higher design freedom of the stereo metamaterials, our work provides a promising way for PIT metamaterial and terahertz slow light device research.