▎ 摘　　要

The polarization-insensitive and tunable plasmon induced transparency (PIT) in a graphene-based terahertz metamaterial are investigated. The cross metal and four square split-ring resonators (SRRs) are used to form the polarization-insensitive metamaterial. The tunable property is obtained by loading a graphene into the structure. Numerical results show that the resonant frequency and the performance of PIT transparency window are flexibly tuned by changing the Fermi energy of graphene layer and relative distance between the cross metal and SRRs, respectively. The PIT transparency windows are maintained at any polarization angles of the incident wave. The proposed system can be used as a refractive index sensor with a sensitivity of 26.6 THz/refractive index unit (RIU) at the transparent peak, and a group delay of 0.9 ps is also obtained for slow-light application. The results show that the proposed nanostructure may find its potential applications in environmental sensors, switches and slow-light devices.