Lidar for autonomous vehicles: trends in lasers and detectors

Lidar sensors provide perception pipelines with low-latency, three-dimensional point clouds, giving geometrically accurate data for the detection of objects, vehicles and pedestrians. In autonomous vehicles, sensor design needs to consider the challenges associated with cities and highways, solar background, as well as adverse weather conditions. We consider the advantages and limitations of different lidar technologies with a concentration on pulsed-time-of-flight lidar. Recent advances in Single Photon Avalanche Diode (SPAD) technology have increased photon-detection efficiency and reduced sources of noise. We review improvements in edge-emitting lasers and VCSELS, showing trends in power and Beam Parameter Product (BPP). For edge-emitting lasers, we review the performance of gain-guided versus index-guided lasers and resulting BPP. For VCSELs, we consider trends with larger diameters, more junctions, and back-side emission. Finally, we offer an overview of lidar technology for autonomous vehicles and suggest a roadmap for improved lasers and sensors.