Single and dual-band electromagnetically induced transparency in a strongly near field toroidal terahertz metamaterial

We demonstrate electromagnetically induced transparency (EIT) in a strongly coupled planar terahertz toroidal metasurface through simulations, theory and experiments. The near -field interaction between a unique toroidal resonator enveloped by a 2 -arc resonator leads to the excitation of EIT in the metamaterial. A modulation in the EIT response of the metasurface is observed by increasing the gap between the resonators, resulting a redshift of the transmission response. Furthermore, we report the excitation of dual -band EIT in the metasurface by introducing an asymmetry in the 2 -arc resonator. A theoretical oscillator model is used to validate the experimental EIT effect, and to gain an in-depth understanding of the coupling mechanism of the proposed geometry. Metasurfaces were fabricated and characterized for each individual resonator geometry as well as the geometries corresponding to the single -EIT design and the dual -EIT design. This study can contribute to the development of slow light devices and ultrafast switches in the terahertz regime.