▎ 摘　　要

In the field of optoelectronics, circular dichroism (CD) has caused great research interest because it is widely used in imaging and biosensing. A new method for dynamically controlling terahertz (THz) CD in metamaterials is proposed. By introducing chirality and graphene to metamaterials, a pair of chiral structures with completely opposite responses to left-handed circularly polarized (LCP) waves and right-handed circularly polarized (RCP) waves are designed. The influencing factors of CD are explored, including the gap of the structure, the linewidth of graphene, and the Fermi level of graphene. The largest CD (Delta R) is 77%. The CD can be actively modulated in a modulation range of 39-77% and the modulation depth is up to 38%. In addition, two-channel and four-channel chiral metasurfaces for near-field imaging are designed in this way. Good imaging effects and on ("1") or off ("0") effects of the multichannel metasurface are demonstrated. This work provides new ideas for the design of tunable metasurfaces and promotes the application of metasurfaces in THz dynamic imaging.