Multi-band terahertz chiral metasurface with giant optical activities and negative refractive index based on T-shaped resonators

A novel chiral metasurface (CMS) based on T-shaped resonators is proposed and investigated numerically. The CMS is composed of a periodic array of bi-layered conjugated fourfold T-shaped structure. The retrieved effective electromagnetic (EM) parameters indicate that the multi-band negative refractive index associated with strong optical activity and circular dichroism (CD) effect is realized in terahertz (THz) region. The physical mechanism is illustrated by analyzing the current density distributions. Due to its exotic chiral optical properties, the proposed CMS is useful for the development of THz devices.