A terahertz sensor based on graphene metamaterial with tunable double plasmon-induced transparency

A terahertz sensor based on graphene metamaterial with double plasmon-induced transparency is proposed, which mainly consists of four graphene elliptical rings and four graphene rectangular strips. The theoretical spectra of the three-resonant oscillator model fit well with the transmission spectra. A double PIT window is formed by the coupling between the bright mode and two quasi-dark modes, and the dynamic tunability of graphene can be used to control the frequency shift and the switch of the double PIT phenomenon. The number of windows can be adjusted by changing the size and Fermi level of different structures. The sensor is unaffected by polarization angle changes. The maximum sensitivity and FOM of the PIT window are 1.50 THz/RIU and 6.89/RIU. In addition, the sensor has a good slow light effect. This terahertz sensor can be used in complex experimental environments due to its flexible tunability. •The double PIT window can be obtained and it is insensitive to polarization.•The frequency shift and switch of the double PIT phenomenon can be controlled.•The number of the window can be changed by changing the size or Fermi level.•The device shows high sensitivity and has a good slow-light performance.