Self-adaptive method for performance enhancement of sweep-velocity-locked lasers

Abstract. Optical frequency-domain reflectometry and frequency-modulated continuous wave (FMCW)-based sensing technologies, such as LiDAR and distributed fiber sensors, fundamentally rely on the performance of frequency-swept laser sources. Specifically, frequency-sweep linearity, which determines the level of measurement distortion, is of paramount importance. Sweep-velocity-locked semiconductor lasers (SVLLs) controlled via phase-locked loops (PLLs) have been studied for many FMCW applications owing to its simplicity, low cost, and low power consumption. We demonstrate an alternative, self-adaptive laser control system that generates an optimized predistortion curve through PLL iterations. The described self-adaptive algorithm was successfully implemented in a digital circuit. The results show that the phase error of the SVLL improved by around 1 order of magnitude relative to the one without using this method, demonstrating that this self-adaptive algorithm is a viable method of linearizing the output of frequency-swept laser sources.