Multi-control plasmon-induced transparency via graphene and bulk Dirac semimetal

Based on graphene and bulk Dirac semimetal (BDS), we proposed a terahertz metamaterial which can realize plasmon-induced transparency (PIT) effect. By independently or jointly tuning the Fermi energy of graphene and BDS, the frequency selection, single frequency optical switch and the double frequency synchronous optical switch can be achieved. The physical mechanism of single PIT effect is explained via electric field distribution and coupled mode theory. In addition, we improve the proposed metamaterial by etching grooves on the BDS gratings and changing the structural parameters of graphene and BDS gratings, which results in a dual-PIT effect. When independently or jointly tuning the Fermi energy of graphene and BDS, the frequency of the dual-PIT peaks can also be tuned, and the quatary frequency asynchronous and triple frequency synchronous optical switch can be achieved. By analyzing the electric field distribution, we found that the double PIT effect is caused by different mode coupling between graphene and BDS gratings. This work provides a new direction for the future design of multi-band filters and optical switch in terahertz band.