  Laser based ranging (LiDAR) - already ubiquitously used in robotics,
industrial monitoring, or geodesy - is a key sensor technology for future
autonomous driving, and has been employed in nearly all successful
implementations of autonomous vehicles to date. Coherent laser allows
long-range detection, operates eye safe, is immune to crosstalk and yields
simultaneous velocity and distance information. Yet for actual deployment in
vehicles, video frame-rate requirements for object detection, classification
and sensor fusion mandate megapixel per second measurement speed. Such pixel
rates are not possible to attain with current coherent single laser-detector
architectures at high definition range imagining, and make parallelization
essential. A megapixel class coherent LiDAR has not been demonstrated, and is
still impeded by the arduous requirements of large banks of detectors and
digitizers on the receiver side, that need to be integrated on chip. Here we
report hardware efficient coherent laser ranging at megapixel per second
imaging rates. This is achieved using a novel concept for massively parallel
coherent laser ranging that requires only a single laser and a single
photoreceiver, yet achieves simultaneous recording of more than 64 channels
with distance and velocity measurements each - attaining an unprecedented 5
megapixel per second rate. Heterodyning two offset chirped soliton microcombs
on a single coherent receiver yields an interferogram containing both distance
and velocity information of all particular channels, thereby alleviating the
need to individually separate, detect and digitize distinct channels. The
reported LiDAR implementation is hardware-efficient, compatible with photonic
integration and demonstrates the significant advantages of acquisition speed,
complexity and cost benefits afforded by the convergence of optical
telecommunication and metrology technologies.
