Polarization-dependent and tunable absorption of terahertz waves based on anisotropic metasurfaces.

Metamaterial absorbers can achieve high-efficiency electromagnetic absorption in a specific band, which have been used in biochemical sensing, photoelectric detection, imaging and other fields. Tunable metamaterial absorbers provide more possibilities for the development of multifunctional electromagnetic absorption devices. Here we propose a tunable and polarization-dependent terahertz metamaterial absorber which can work for both linearly and circularly polarized waves. By introducing single layer graphene and vanadium dioxide (VO), switching between the two working states and wide-range tuning of the absorption efficiency are realized. When VO is in insulating state, the absorber shows different tunable absorption performance for the x- or y-polarized terahertz waves, in which the maximum absorption rate is close to 100%. When VO is in metallic state, the metasurface behaves as a chiral absorber, and the maximum absorption difference between the two circular polarizations is about 0.45, while the tuning efficiency reaches 86.3%. Under the two working conditions, the absorber can maintain efficient absorption with a large incident angle. In addition, as an application exploration of the absorber, we demonstrated its application in tunable and polarization multiplexed near-field image display.