Versatile terahertz graphene metasurface based on plasmon-induced transparency

A monolayer terahertz graphene metasurface is designed to achieve tunable plasmon-induced transparency (PIT) effect in two perpendicular polarization directions based on surface plasmon polariton resonance. The penta-frequency and dual-frequency switch can be easily implemented by adjusting the Fermi levels of graphene, and the switch has excellent performances including modulation degree of amplitude (81.4 % < MDA < 97.1 %) and insertion loss (0.01 dB < IL < 0.04 dB). Moreover, the metasurface has high sensitivity, which can be up to 30500 nm/RIU. Also, the designed PIT metasurface has a good slow light effect, and group indexes are respectively 1100 and 2396 corresponding to x-polarized and y-polarized light. This work demonstrates that graphene metasurface has potential applications in switch, sensor and slow-light devices.