Abstract
We report on a laser frequency sweep linearization method by iterative learning pre-distortion for frequency-modulated continuous-wave (FMCW) light detection and ranging (LiDAR) systems. A pre-distorted laser drive voltage waveform that results in a linear frequency sweep is obtained by an iterative learning controller, and then applied to the FMCW LiDAR system. We have also derived a fundamental figure of merit for the maximum residual nonlinearity needed to achieve the transform-limited range resolution. This method is experimentally tested using a commercial vertical cavity surface-emitting laser (VCSEL) and a distributed feedback (DFB) laser, achieving less than 0.005% relative residual nonlinearity of frequency sweep. With the proposed method, high-performance FMCW LiDAR systems can be realized without expensive linear lasers, complex linearization setups, or heavy post-processing.
Highlights
Light detection and ranging (LiDAR) technologies have many applications ranging from scientific researches, industrial manufacturing to robotics and autonomous vehicles [1,2]
As a proof of concept, we experimentally demonstrated an frequency-modulated continuous-wave (FMCW) LiDAR using a commercial vertical-cavity surface-emitting laser (VCSEL) and a distributed feedback (DFB) laser
The goal of the Iterative learning control (ILC) process is to find a pre-distorted laser drive voltage waveform ud(t) that leads to the desired laser frequency sweep νd(t), a triangle waveform with period 2Tramp, without a priori knowledge of the dynamic behavior of the laser
Summary
Light detection and ranging (LiDAR) technologies have many applications ranging from scientific researches, industrial manufacturing to robotics and autonomous vehicles [1,2]. Compared to the conventional pulsed time-of-flight method, frequency-modulated continuous-wave (FMCW) technology is able to achieve high resolution without requiring fast electronics or high optical power, and is immune to direct sun light and interference from other LiDAR transmitters, thanks to coherent detection [1,3]. It is capable of simultaneously detecting target position and velocity in a single measurement through the Doppler frequency shift [4]. Residual nonlinearity will degrade the resolution and signal-tonoise-ratio (SNR) of LiDAR detection [6]
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