Photonics-Enabled Millimeter-/Terahertz-Wave Signal Processing and Applications

Radio communication in the millimeter-wave (mmW) and terahertz-wave (THz) bands holds great potential for ultra-high data rates and low-latency services in 6G and beyond networks. However, extremely high free-space loss and weak penetration remain significant bottlenecks, making it challenging to transmit signals over long distances and in areas with barriers, walls, and obstacles. In addition, simplifying transceivers and antenna sites is crucial for facilitating practical applications. All-photonic technology for mmW/THz signal processing can play a pivotal role in overcoming inherent challenges and enabling new communication features and applications. In this paper, we present various photonic technologies for the generation, transmission, reception, and processing of mmW/THz signals. System concepts and proof-of-concept demonstrations using the proposed technologies for different applications, including fixed wireless access, mobile backhaul, mmW/THz signal relay, routing, and switching, are presented. The concept of a reconfigurable fiber–wireless network and a proof-of-concept demonstration of high-speed tunable intermediate frequency-over-fiber transmission, capable of supporting reconfigurable networks, are also presented. The challenges and outlooks of the technology for practical applications are also discussed.