Triple-Band Terahertz Chiral Metasurface for Spin-Selective Absorption and Reflection Phase Manipulation

In this paper, a triple-band terahertz chiral metasurface is proposed, which could realize spin-selective absorption (SSA) effect and efficient independent phase manipulation in three distinct frequency bands. Through the simulation of the surface current distribution, we explain the mechanism of the triple-band SSA effect. Furthermore, the introduction of Pancharatnam–Berry phase endows the metasurface with the ability to manipulate the reflection phase at the chiral resonance frequencies, which enabled simultaneous amplitude and phase manipulation of CP waves through different phase coding strategies. To test this concept, two terahertz SSA-coding metasurfaces were designed and simulated, which have the function of four-beam splitting and vortex wave anomalous reflection, respectively. These simple-structured multifunctional devices demonstrate the application prospects of the metasurface in terahertz chiral sensing, imaging, secure communications, etc.