面向调频连续波激光探测的复合环路动态光锁相机理与技术研究

Optical frequency-modulated continuous-wave (FMCW) interferometry allows fundamental improvement in the performance of coherent optical measurement and has thus long been regarded as a valuable tool for high precision optical measurement and sensing. The performance in terms of the measurement range, precision, and spatial resolution is limited by the laser source. The spatial resolution is determined by the total chirp bandwidth, while the coherence of the laser source dictates the achievable measurement range. Therefore, the key issue lies in the broadband linear sweep with high coherence during the sweep process. Until recently, FMCW laser sources have suffered from a trade-off between the chirp bandwidth and the coherence and chirping linearity due to the fact that fundamental limit of the laser physics has hindered the simultaneous achievement of high coherence, namely, low phase noise and narrow linewidth, and precise broadband tuning for conventional laser sources. .In order to achieve high-performance FMCW measurement, based on the in-depth investigation on the laser phase and frequency control and modulation mechanisms, in this research, dynamic optical phase-locking (OPLL) is proposed to overcome this trade-off. Relying on the composite phase and frequency control loop and the short delay interferometry, it enables broadband dynamic control of the laser phase and frequency properties with high bandwidth. By establishing a theoretical model for the dynamic OPLL, the synergistic effect and the efficiency of the composite loop have been numerically evaluated. Experimental demonstration based on fiber laser has achieved broadband chirping with nonlinear calibration and dynamic phase and frequency reduction, overcoming the trade-offs between chirp range and coherence. It also reveals the evolution of coherence properties against the measurement range with the action of dynamic OPLL. This relation allows constituting the systematic optimization model, and finally leading to the generation of broadband chirping with high linearity and coherence during the chirp. In this case, we realize optical FMCW measurement system with long measurement range, high precision, and spatial resolution. We also build evaluation test bench and application based verification is carried out. .This research presents an effective solution for the broadband and high precision control of the laser phase and frequency, providing important fundamentals and technical support for the research field of coherent measurement and for relevant communities.

调频连续波激光探测技术可多方面提升激光测量的性能，代表着该领域的主要发展方向，宽范围、高相干的激光线性扫频是其核心技术。然而，需要解决光频扫描范围与相干性相互制约的基础科学问题。.本项目围绕激光相频控制机制开展研究，提出动态光锁相控制的光扫频方法，采用复合环路相频调控和短延迟自相干鉴频鉴相技术，实现宽范围、高带宽的激光相频控制。通过研究复合环路的协同机制及效率，校正扫频非线性、压缩扫频时的动态线宽，抑制激光的动态相频噪声，解决扫频范围和相干性之间的矛盾，生成宽范围线性扫频的高相干激光。研究光锁相控制下光相干性、线宽、相频噪声之间的动态演化规律，建立调频连续波激光测量系统，实现长距离、高精度、高分辨率的光调频连续波探测。本项目为解决激光的宽范围、高精度相频控制提供有效的技术途径，为我国相干光测量技术的发展提供重要的理论基础和技术储备。

激光探测技术是实现高精度、高分辨的多维信息感知和获取的有效技术手段。随着近年来信息技术的发展，各类新型应用对其提出了新的需求和挑战。激光调频连续波（FMCW）相干探测技术，将FMCW测量与激光技术进行了有机结合，取得关键性能的提升，为三维成像、自动驾驶、分布式传感等诸多应用领域提供了有效的技术手段，成为激光探测技术的重要发展方向。激光FMCW相干探测技术的关键是实现宽范围、高相干、高线性的扫频激光，然而受制于激光原理，迫切地需要解决光频扫频范围与相干性相互制约的基础科学原理。.本项目围绕激光相频调控机理展开言研究，提出了基于复合环路动态光锁相（OPLL）技术的激光扫频方法，研究复合环路动态OPLL技术，包括基于非平衡马赫曾德干涉的延迟自相干鉴频鉴相技术、直调外调相结合的复合环路激光相频调控技术，研究了复合环路中多环的协同机制和控制方法，揭示了复合环路动态OPLL中激光相频噪声和系统噪声在不同延迟干涉长度下的演化规律和噪声传递机理，建立了系统优化设计模型，实现了宽范围线性扫频的扫频非线性校正和相干性增强，实验产生了扫频范围8.5GHz、扫频速率170GHz/s、非线性RMS误差小于±50kHz的高相干线性扫频。搭建了基于光频域反射的光纤链路测试平台，实验结果表明，该系统能支持瑞利散射测量范围超过140km，菲涅尔反射测量范围超过240km，在整个测量范围内达到了cm量级的空间分辨率，其空间-距离分辨力达10E-7量级。该结果有效验证了系统的性能，验证了系统在长距离、高精度测量中的应用价值。