Tunable polarization-nonsensitive electromagnetically induced transparency in Dirac semimetal metamaterial at terahertz frequencies

Tunable polarization-nonsensitive electromagnetically induced transparency (EIT) based on Dirac semimetal films (DSF) at terahertz frequencies is numerically studied in this paper. We first numerically investigate the EIT effect in a DSF-based terahertz metamaterial structure comprising a DSF strip and two DSF L-shaped resonators. To achieve the polarization-nonsensitive EIT effect, we introduce one vertical strip and two more L-shaped resonators to the above structure. The transmission spectra of the new structure show strong polarization-nonsensitive characteristic because of the fourfold symmetry. By analyzing the surface currents and electric field distribution at the resonant frequencies, we demonstrate that an EIT effect arises from the bright–bright mode coupling. Moreover, the polarization-nonsensitive EIT structure exhibits a blue shift with the increase in the Fermi energy of the DSF without having to re-optimize its geometrical parameters. Our study opens a new path for developing terahertz devices such as terahertz switches.