中文摘要：

这篇文章一起介绍活跃的光钟，联合一个原子激光的激光物理的特殊激光，坏洞的煤气的激光，超级洞的稳定的激光和光原子钟的原则和技术。作为一个简单例子，基于热锶，原子横梁显示出的一只活跃的光钟 0.51 Hz 的量有限线宽，它对激光洞长度噪音感觉迟钝，并且可以超过记录最狭窄 Hg 离子的 6.7 Hz 光钟和很最近的光格子钟的 1.5 Hz。估计 0.1 Hz 一个秒不稳定性和 0.27 Hz 不确定性仅仅由相对论的 Doppler 效果是有限的，并且能被冷原子改进。

英文摘要：

This article presents the principles and techniques of active optical clock, a special laser combining the laser physics of one-atom laser, bad-cavity gas laser, super-cavity stabilized laser and optical atomic clock together. As a simple example, an active optical clock based on thermal strontium atomic beam shows a quantum-limited linewidth of 0.51 Hz, which is insensitive to laser cavity-length noise, and may surpass the recorded narrowest 6.7 Hz of Hg ion optical clock and 1.5 Hz of very recent optical lattice clock. The estimated 0.1 Hz one-second instability and 0.27 Hz uncertainty are limited only by the relativistic Doppler effect, and can be improved by cold atoms.