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 (VO₂) to enable precise beam steering. Designed with a single-layer metasurface composed of VO₂ 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.