Frequency Modulated Continuous Wave and Time of Flight LIDAR with Single Photons: a Comparison

In this study, we delve into the characteristics and compare the performance of two prominent Light Detection and Ranging (LIDAR) technologies: Frequency Modulated Continuous Wave (FMCW) and Time of Flight (ToF). We construct a setup capable of performing both LIDAR methods at the single photon level using a Superconducting Nanowire Single Photon Detector (SNSPD). We demonstrate the superior capabilities of FMCW LIDAR under low power conditions, being able to reconstruct 3D environments with probe signals of 20 nW compared to the > 100 nW required by ToF LIDAR with identical targets, integration time, and background interference. We also introduce a median de-noising filter to effectively combat typical 'salt and pepper' noise found in the FMCW images, further enhancing the performance. Using FMCW LIDAR we achieve a resolution of +/- 25 mm, mainly limited by non-linear phase noise in the probe laser. Compared to ToF's +/- 3 mm, mainly limited by the timing jitter of the setup. The results demonstrate the benefits of FMCW LIDAR in terms of power efficiency make it a compelling choice for LIDAR systems at the single photon level, particularly in power-conscious applications.