Photonic Technology for Millimeter-Wave and Terahertz-Wave Communications in IMT-2030 and Beyond

Radio communications in the millimeter-wave and terahertz-wave bands are promising for high-speed, low-latency services. However, several challenges—such as high free-space loss, weak penetration, and limited coverage—remain as bottlenecks, making the deployment of high-frequency radio communications challenging. Photonic technology and its convergence with radio technologies can play a vital role in enabling high-frequency radio communications. In this article, we present key photonic technologies, including a high-speed fiber–wireless bridge system for fixed wireless access and emergency communications, transparent relay and routing of radio signals for coverage extension, and the simultaneous generation, transmission, and reception of multiple radio signals, to overcome these bottlenecks. For each technology, we outline the system concept and provide a proof-of-concept demonstration. The achieved results highlight the potential of the proposed solutions and could pave the way for deploying radio access networks in the millimeter-wave and terahertz-wave bands for IMT-2030 and beyond.