Dynamic Blazed Grating Mechanism in An Air Gap Tunable Terahertz Metasurface Based Dynamic Beam Steering Device

Next-generation wireless sensing and communication will require efficient terahertz beam steering to enhance spatial coverage and establish non-line-of-sight links. Beam steering can be achieved using tunable metasurfaces, and the air gap tunable metasurfaces are particularly promising due to their good performance and high efficiency, resulting from the absence of lossy material in the tuning gap. In this article, we present an air gap tunable terahertz metasurface designed to operate primarily at 145 GHz. Importantly, we show that this device constitutes a terahertz blazed grating, whose blaze angle is dynamically tuned by adjusting the metasurface air gap. This enables a continuous, low-loss selection of the fractions of energy radiated in the zeroth and first diffraction orders. The device’s operation has been characterized experimentally, and the results confirm the dynamic blazed grating mechanism. The theoretical foundation is also shown to reveal the functional limitations of this mechanism in beam steering.