Terahertz liquid crystal programmable metasurface based on resonance switching

A programmable metasurface based on liquid crystal is of great significance to versatile dynamic wave manipulation such as beamforming and beam steering. One of the biggest obstacles currently is the lack of a simple way to multi-bit programming scheme for massive electrically addressable arrays, which limits its application and magnifies drawbacks like unavoidable symmetrical beam diffraction. Here, we put forward the concept of a liquid crystal metasurface based on a resonance switching mechanism for quasi-2-bit coding control, which is established upon interdigital structure electrodes. This enables a more elaborate control of meta-unit and a quasi-2-bit modulation based on a universal binary coding system to be realized. Our design could suppress unwanted -1 diffraction order with a maximum single-beam scanning angle of ± 21° under active beam manipulation. This concept paves the way for a feasible and robust multi-bit coding scheme of a liquid crystal metasurface, which is promising for THz applications such as spatial light modulators and wireless communication.