Photonic Radar for 3D Imaging: From Millimeter to Terahertz Waves

With the development of 5G and other technologies, radar imaging techniques in high-frequency bands up to the terahertz (THz) range have attracted considerable attention. In particular, the photonic radar technique benefits from the unique advantages of optical devices, including an ultrawide and flexible bandwidth of more than 100 GHz, leading to submm-order range resolution, reduced phase noise, and flexible optical links. This article reviews recent progress in photonic radar systems from the millimeter wave to THz bands, including the hardware components, imaging technology, and radar imaging applications, and discusses the potential high-resolution imaging techniques enabled by photonic radar systems.