Double E-shaped toroidal metasurface with high Q-factor Fano resonance and electromagnetically induced transparency

A double E-shaped toroidal dipole metasurface is designed with the high Q-factor Fano and classical electromagnetically induced transparency (EIT) phenomena in the microwave frequency range. With the introduction of an asymmetric structure, the sharp Fano resonance can be excited and acquired a quite high Q-factor of 134 at a lower frequency of 4.58 GHz. It can be numerically and experimentally demonstrated that the singularity Fano response of designed construction is caused by the intensive toroidal dipole. In addition, due to destructive interference between the intensive toroidal dipole and electric dipole, the transmission peak of EIT can reach 0.95 with a Q-factor of 50 at 10.18 GHz. By calculating and comparing the radiated power of multipoles, the enhanced toroidal dipole response can be further verified. The designed planar toroidal dipole metamaterial with simple construction may have many possible applications in toroidal moment generators, sensing, and slow-light devices.