The rise of topological valley photonics heralds a new era in photonic integrated circuits featuring low-loss, compact designs with robust light transport through sharp corners. However, most demonstrations of valley photonic devices only focus on the robust waveguiding of light with suppressed radiation leakage. Here we harness the conical radiation of leaky valley photonic crystals to demonstrate a topological leaky-wave antenna (LWA) that unifies leaky and guided topological edge states on a single silicon chip. We demonstrate a wide-range beam scanning of 120° in the polar angle with a maximum gain of 15 dBi using a single-branch topological LWA. In addition, the 3-branch LWA enables beam scanning over 75% of the entire three-dimensional solid-angle space. We further demonstrate frequency-division demultiplexing of 3 terahertz wireless links, each radiating 120° apart to collectively deliver high-gain omnidirectional full-space coverage, achieving an aggregate data rate of 72 Gbps. Furthermore, we demonstrate bidirectional dual-channel terahertz wireless links, where the time-reversal-symmetric topological LWA simultaneously receives a real-time high-definition video stream and transmits on-chip signals into free space at a data rate of 24 Gbps. Our on-chip leaky topological antennas provide a versatile platform for the next generation 6G and beyond (XG) cellular networks, imaging, terahertz Wi-Fi (TeraFi), and terahertz detection and ranging (TeDAR).
Wang et al. (Mon,) studied this question.