Dual chirped micro-comb based parallel ranging at megapixel-line rates

Abstract: Laser based ranging (LiDAR) - already ubiquitously used in industrial monitoring, atmospheric dynamics, or geodesy - is key sensor technology. Coherent laser ranging, in contrast to time-of-flight approaches, is immune to ambient light, operates continuous wave allowing higher average powers, and yields simultaneous velocity and distance information. State-of-the-art coherent single laser-detector architectures reach hundreds of kilopixel per second rates. While emerging applications such as autonomous driving, robotics, and augmented reality mandate megapixel per second point sampling to support real-time video-rate imaging. Yet, such rates of coherent LiDAR have not been demonstrated. Here we report a swept dual-soliton microcomb technique enabling coherent ranging and velocimetry at megapixel per second line scan measurement rates with up to 64 spectrally dispersed optical channels. It is based on recent advances in photonic chip-based microcombs that offer a solution to reduce complexity both on the transmitter and receiver sides. Multi-heterodyning two synchronously frequency-modulated microcombs yields distance and velocity information of all individual ranging channels on a single receiver alleviating the need for individual separation, detection, and digitization. The reported LiDAR implementation is hardware-efficient, compatible with photonic integration, and demonstrates the significant advantages of acquisition speed afforded by the convergence of optical telecommunication and metrology technologies. We anticipate our research will motivate further investigation of frequency swept microresonator dual-comb approach in the neighboring fields of linear and nonlinear spectroscopy, optical coherence tomography.