A liquid crystal-based multi-bit terahertz reconfigurable intelligent surface

Recently, the growing interest in reconfigurable intelligent surface (RIS) technology has spurred extensive research on its utilization in the terahertz (THz) regime. The reconfiguration of the THz field empowered by the RIS holds great significance for various practical RIS-aided implementations at THz frequencies. In this study, we present a multi-bit liquid crystal-based RIS that allows for the programmable control of THz waves. The proposed RIS is characterized by an achievable 3-bit working state as well as a near 270° maximum phase shift around 0.28 THz. This high degree of freedom in manipulating the phase of the reflected field provides flexibility in terahertz spatial beam reconfigurations. We show that the terahertz single-beam pattern can be steered continuously from 5° to 55° toward the desired angles while also allowing the adjustment of the beam number and beamwidth. Through this demonstration, we aim to contribute to the advancement of RIS technologies in the terahertz regime, paving the way for various RIS-aided applications such as THz wireless communications and beyond.