Chiral terahertz multifunctional metasurface based on Dirac semimetal for wavefront manipulation

Tunable chiral metasurfaces provide more options for multifunctional terahertz devices, which has attracted extensive attention from researchers. In the paper, we proposed a double split ring tunable chiral metasurface based on Dirac semimetals (DSM). For linearly polarized waves are incident, the DSM metasurface acted as a linear-to-circular (LTP) polarization converter at 1.36 THz. For circularly polarized waves are incident, the strong chiral properties of the metasurface can be dynamically controlled by changing the Fermi level of the DSM. The maximum circular dichroism (CD) of the chiral metasurface is 0.95 at 1.39 THz. In addition, based on the theory of Panchalatnam-Berry (PB) phase, multifunctional applications including beam focusing, deflection, and splitting can be achieved through the reasonable design of meta-atoms with tailored phase distributions. Furthermore, the controllable near field image was realized by arranging the meta-atoms of the original and mirror metasurface. These results are expected to have broad application prospects in terahertz communication, image processing and other fields.