Demonstration of 2D Optoelectronic THz-Wave Beam Steering

Advanced two-dimensional (2D) beam steering is critical for unlocking the full potential of terahertz (THz) systems in future 6G communications and high-resolution imaging. However, realizing wide-angle, high-speed, and high-precision 2D beam control in a compact and simple THz front end remains challenging. This paper experimentally demonstrates a photonics-assisted 2×2 THz antenna array that enables flexible 2D beam steering, 2D beam hopping, and fast 2D beam scanning around the 300-GHz band. The proposed front end is an integrated THz photomixer composed of a 2×2 microstrip patch antenna (MPA) array directly fed by InGaAs/InP uni-traveling-carrier photodiodes (UTC-PDs) on a silicon carbide (SiC) substrate. The relative phases of the four radiating elements are precisely controlled by an optical phased array (OPA), providing a fully decoupled and low-latency phase control mechanism. Experimentally, we realize 2D beam steering and 2D beam hopping among three representative beam directions at an elevation angle of 25° with azimuth angles of 60°, 180°, and 300°. Furthermore, continuous 2D beam scanning is demonstrated at a fixed elevation of 25°, achieving a full 360° azimuth sweep within 0.43 s while maintaining high beam quality. These results confirm that the proposed 2×2 photomixer-based array offers a practical and robust solution for agile 2D THz beam manipulation, and holds strong promise for future 6G wireless links and THz image sensing applications.