中文摘要：

自从20世纪激光发明以来,激光的应用已经深入到我们生活的各个方面,如光刻机、激光3D打印、激光医疗、大型激光干涉引力波探测等。在科学研究上,激光是一种不可或缺的重要光源,它以其优异的光谱特性被应用于许多研究领域,尤其是超窄线宽的高稳定度激光可以作为一双独特＂眼睛＂,能够用来观察原子分子的微观物理世界。如果以这种高稳定度激光来探测原子或离子的光谱特征,并将激光频率锁定在原子或离子的能级跃迁上,能形成计时无比精准的＂光学原子钟＂。这种新型的时钟具有前所未有的计时精度,它的累积误差将可以做到从宇宙起源（137亿年前）至今仍小于1秒!获取这种超窄线宽的高稳定度激光是一项关键且非常重要的技术,文章详细介绍了该项技术的发展历程和基本原理,以及它的几项重要的用途和前沿进展。

英文摘要：

Since its invention in the 20 th century, lasers have permeated every aspect of our daily life. With its exceptional spectral features it is now an indispensable light source, and lasers have been widely adopted in many areas of scientific endeavor, including laser photolithography, 3D printing, laser medicine, and large-scale gravitational wave detectors based on laser interferometry. In particular, lasers with ultra- narrow linewidth and high frequency stability act as unique ＂eyes＂ that enable us to peer through the micro world of atoms and molecules. This type of laser is used to probe the spectral features of atoms or ions and can be locked onto their transitions,leading to the development of an ＂optical atomic clock＂ with unprecedented precision in timekeeping. In fact, the optical atomic clock is incapable of accumulating just one wrong second if it started to tick at the moment of the creation of the universe some 13.7 billion years ago. How to obtain such a laser is by no means a trivial task, as it involves many key scientific technologies. This paper reviews the principles and historic development of laser frequency stabilization. We also describe many important applications and future developments of ultra-stable lasers.