Switchable Terahertz Beam Steering with Near‐Perfect Ordinary Transmission

This study introduces a reconfigurable metasurface that achieves transmission control across a broadband terahertz (THz) frequency range by leveraging the phase transition property of vanadium dioxide (VO 2 ) to enable precise beam steering. Designed with a single‐layer metasurface composed of VO 2 split‐ring resonator (SRR) unit structures, this device offers switchable THz beam steering upon actuation with a global temperature change. At high temperatures corresponding to the “ON” state, the metasurface exhibits frequency‐dependent THz beam steering at large angles for crosspolarized THz transmission, as demonstrated both numerically and experimentally. At room temperature and in the “OFF” state, it achieves near‐perfect ordinary transmission for the incident THz light, without distorting the incoming light. The reconfigurable metasurface demonstrates an average modulation depth of 95% with a maximum value of 99.8% at the designed deflection angles. This innovative approach indicates the potential advanced applications in THz technology, including communications, imaging, and sensing, which require high‐performance, efficient, and reconfigurable THz deflectors.