基于光电锁相环的高线性FMCW激光雷达频率调谐技术  

High Linearity FMCW Lidar Frequency Tuning Technique Based on Electro-optical Phase-locked Loop

作　　者：吴子涵 袁国慧 赵浩浩 孙亮 王卓然 WU Zihan;YUAN Guohui;ZHAO Haohao;SUN Liang;WANG Zhuoran(School of Electrical and Information Engineering,Quzhou University,Quzhou 324000,China;Yangtze Delta Region Institute(Quzhou),University of Electronic Science and Technology of China,Quzhou 324003,China;School of Information and Communication Engineering,University of Electronic Science and Technology,Chengdu 610054,China)

机构地区：[1]衢州学院电气与信息工程学院,衢州324000 [2]电子科技大学长三角研究院(衢州),衢州324003 [3]电子科技大学信息与通信工程学院,成都610054

出　　处：《光子学报》2024年第6期110-121,共12页Acta Photonica Sinica

基　　金：浙江省自然科学基金(No.Y23F050001);四川省自然科学基金(Nos.2023NSFSC0492,2022NSFSC0460);电子科技大学医工交叉联合基金(No.ZYGX2021YGLH214);衢州市财政资助科研项目(Nos.2023D001,2023D020)。

摘　　要：搭建了可调谐半导体激光器扫频非线性校正系统,研究了锯齿波调制下半导体激光器的扫频非线性特性,将光电锁相环技术引入调频连续波光源系统中,提出在预失真校正电流基础上采用光电锁相环的方法来克服扫频非线性,以防止大范围扫频非线性频差导致的失锁现象。基于调频连续波激光测距实验,验证光频线性化的效果,并分析了扫频非线性对精确距离测量的影响。实验结果表明,经过非线性校正后,激光器输出光频与理想线性光频差的均方根误差缩小到23.7 MHz(减小为校正前的1/219),残余非线性仅余0.0339%,1-r2的数量级达到10-7,测距实验中得到的目标厚度误差在不同测量距离下在0.05 mm~0.15 mm之间变化,表明非线性校正取得了良好的效果。In recent years,Light Detection and Ranging(Lidar)technology has gained significant attention due to digital advancements and its widespread applications in various domains such as active target detection,industrial manufacturing,robotics,and autonomous driving.The increasing demand for high-precision measurement technology has led to the Frequency-Modulated Continuous Wave(FMCW)approach emerging as a promising tool for achieving enhanced accuracy and resolution at lower received optical power,enabling direct detection target position and velocity.FMCW offers several advantages,including improved anti-interference ability,cost-effectiveness,wider measurement range,and faster measurement accuracy.However,it is essential to note that FMCW laser ranging relies on the ideal linear frequency modulation assumption,which can be distorted by strong nonlinearity and thermal effects of the tunable laser itself,resulting in substantial distortion of ranging results within a narrow frequency range.This issue becomes particularly critical for high-performance Lidar systems.In this manuscript,we propose a nonlinear correction system for tunable semiconductor laser frequency scanning,using a 1550 nm DFB laser modulated with sawtooth waves to create beat signals.An iterative algorithm is employed initially to prevent lock loss due to large frequency differences,followed by an Electro-Optic Phase-Locked Loop(EO-PLL)which adjusts the pre-distortion current to effectively suppress nonlinearity and achieves linear light tuning.The impact of this linearization on FMCW Lidar resolution is confirmed through experiments measuring the thickness of target objects.Following the nonlinear correction of the semiconductor laser's frequency sweeping,the power spectra of the beat signal are compared in three scenarios:the initial state,pre-distortion,and EO-PLL.It can be observed that the initial beat signal has a wider frequency spectrum with many other frequency components.After pre-distortion correction,the spectrum slightly narrows,and the

关 键 词：调频连续波 半导体激光器 锯齿波调制 扫频非线性校正 光电锁相环 

分 类 号：TN958.98[电子电信—信号与信息处理]