激光线宽作为表征激光相干性的重要参数，自激光技术诞生以来就备受人们关注。窄线宽激光器由于光谱纯度高、相干长度长、相位噪声低等优点，被广泛应用于引力波探测、冷原子物理、相干光通信、光学精密测量，以及微波光子信号处理等领域。随着现代信息技术的发展，窄线宽激光器作为这些应用的核心光源，在固有的线宽、噪声等参数得到进一步优化的同时也被期望拥有一些新的性能，如参数的极致调控、时频超稳、波长调谐，以及波长扫描等。激光本征线宽源于自发辐射噪声，激光器线宽压缩的发展历程是研究人员与自发辐射噪声对抗的历程。纵观窄线宽激光的发展历史，激光腔构型从简单的两个反射镜构成的单主腔、多布拉格反射面（DBR）构成的单主腔、分布反馈（DFB）结构构成的单主腔，到激光单主腔加固定单外腔，再到波长自适应分布弱反馈激光构型，其核心思想都是利用反馈信号对自发辐射噪声进行抑制。本文以激光主腔构型的演化发展为叙述脉络，总结窄线宽激光技术的研究进展，对比激光谐振腔构型在激光线宽压缩、噪声抑制思想上的异同，最后重点介绍新近发展的波长自适应分布弱反馈窄线宽激光器，对该类新型激光器的物理思想、核心器件和系统性能进行分析和讨论。

Laser linewidth, an important parameter characterizing laser coherence, has attracted considerable attention since the dawn of laser technology. Narrow-linewidth lasers have been widely used in the fields of gravitational wave detection, cold atomic physics, coherent optical communication, optical precision measurement, and microwave photonic signal processing because of their high spectral purity, long coherence length, and low phase noise. With the development of modern information technology, narrow-linewidth lasers, as the core light source for these applications, are expected to have some new properties, such as extreme tuning of parameters, time-frequency ultrastability, wavelength tuning, and wavelength sweeping, while the intrinsic linewidth, noise, and other parameters are further optimized. The intrinsic linewidth of a laser originates from spontaneous radiation noise; to eliminate the spontaneous radiation noise, researchers are focusing on the development of linewidth compression of narrow-linewidth lasers. Throughout the development history of narrow-linewidth lasers, the laser cavity configuration from a simple two-mirror structure, the distributed Bragg reflector (DBR), the distributed feedback (DFB) main cavity configuration to the external cavity configuration and finally to the wavelength adaptive distributed weak feedback configuration, whose core idea is to use the feedback signal on the spontaneous radiation noise suppression. This paper takes the evolutionary development of laser main cavity configuration as the narrative vein, summarizes the research progress of various narrow linewidth laser technologies, and compares the similarities and differences of various laser cavity configurations in the laser linewidth compression and noise suppression. Furthermore, this paper focuses on the newly developed wavelength-adaptive distributed weak feedback narrow-linewidth lasers. Moreover, it analyzes and discusses the physical concept of narrow-linewidth lasers as well as the core devices and system performance based on this type of lasers.