Multimode Multiplexing Optical Phased Array for Enhanced Coherent LiDAR

The growing demand for LiDAR systems has accelerated the development of high‐performance beam steering technologies, among which optical phased arrays (OPAs) are promising candidates for next generation all‐solid‐state beam steering solutions. Nevertheless, conventional OPAs relying on wavelength tuning for longitudinal beam steering face a bottleneck in field of view (FOV) due to low wavelength tuning efficiency. A multimode multiplexing silicon on‐chip OPA with high wavelength tuning efficiency and wide FOV is proposed and demonstrated in this work. High performance mode‐independent power splitters, mode multiplexers, and other multi‐mode compatible devices of the multimode OPA are optimized and experimentally implemented. The multimode grating waveguide antenna emits distinct optical modes into free space, resulting in a 0.7°/nm wavelength tuning efficiency for each antenna. Optimized sparse antenna distribution is introduced to create a wide, seamless, and grating‐lobe‐free FOV of 60° × 42° under a tunable wavelength range of only 60 nm within a single aperture. Furthermore, a 4D coherent LiDAR experiment based on the multimode OPA and a frequency‐modulated continuous wave (FMCW) system is performed. The superior performance and practical applicability prove that a new paradigm of OPA is established by the work for optical sensing, optical metrology, and free‐space optical communication applications.