Speeding up long-range coherent LiDAR

An illustration of LiDAR waves. Credit: Johann Riemensberger - LiDAR is a technique used for measuring distances with laser light. In a study published in Nature, researchers at EPFL show a new way to speed up a type of LiDAR engine by using photonic circuits. Light detection and ranging (LiDAR) comprised an array of techniques using laser light to measure distances by multiplying the time delay between transmitted and received optical signals with the speed of light. Modern 3D LiDAR sensors combine high lateral/vertical and radial resolution, and are key components in the ongoing revolution of level 4 and 5 self-driving cars. The prominence of 3D LiDAR sensing has its roots in 2007 DARPA autonomous driving challenge with the introduction of the first Velodyne spinning laser array sensors measuring up to 128 laser lines in parallel. Most modern LiDAR sensors rely on the time-of-flight operation principle where short pulses or pulse patterns are emitted from the sensor aperture and the power of back-reflected light is detected using a square-law photodetector.