Controllable transmissive-reflective phase distribution and circular dichroism switchable terahertz chiral metasurface

The ability to simultaneously achieve circular dichroism (CD) and wavefront manipulation is important for applications such as detection and imaging, and usually such metasurfaces operate only in transmission or reflection space, making it difficult to achieve full-space modulation. In this paper, we design a terahertz chiral metasurface composed of VO 2 open rings and silicon pillars. The metasurfaces have independent phase distributions and CDs in the reflective space at 0.8 THz and the transmissive space at 2.2–2.5 THz, respectively, and the reversible switching is realized by changing the temperature. Based on the switchable characteristics of the full-space phase distribution, the switching of the transmitted and reflected focused vortex beams is simulated. Based on the switchable property of full-space CD, the switching of transmitted and reflected near-field imaging is simulated. Holographic imaging with full-space four-channel polarization multiplexing is simulated by combining the switchable properties of phase distribution and CD. The proposed metasurface is expected to be applied to terahertz encryption and communications.