Hänsch Theodor W
Max-Planck Institute of Quantum Optics, Garching, and Department of Physics, Ludwig-Maximilians University Munich, Germany.
Chemphyschem. 2006 Jun 12;7(6):1170-87. doi: 10.1002/cphc.200600195.
Optical frequency combs from mode-locked femtosecond lasers have revolutionized the art of counting the frequency of light. They can link optical and microwave frequencies in a single step, and they provide the long missing clockwork for optical atomic clocks. By extending the limits of time and frequency metrology, they enable new tests of fundamental physics laws. Precise comparisons of optical resonance frequencies of atomic hydrogen and other atoms with the microwave frequency of a cesium atomic clock are establishing sensitive limits for possible slow variations of fundamental constants. Optical high harmonic generation is extending frequency comb techniques into the extreme ultraviolet, opening a new spectral territory to precision laser spectroscopy. Frequency comb techniques are also providing a key to attosecond science by offering control of the electric field of ultrafast laser pulses. In our laboratories at Stanford and Garching, the development of new instruments and techniques for precision laser spectroscopy has long been motivated by the goal of ever higher resolution and measurement accuracy in optical spectroscopy of the simple hydrogen atom which permits unique confrontations between experiment and fundamental theory. This lecture recounts these adventures and the evolution of laser frequency comb techniques from my personal perspective.
锁模飞秒激光器产生的光学频率梳彻底改变了光频率计数技术。它们能一步将光学频率与微波频率联系起来，还为光学原子钟提供了长期缺失的精密机制。通过拓展时间和频率计量的极限，它们开启了对基本物理定律的新测试。将氢原子及其他原子的光学共振频率与铯原子钟的微波频率进行精确比较，正在为基本常数可能的缓慢变化设定灵敏界限。光学高次谐波产生正将频率梳技术拓展到极紫外波段，为精密激光光谱学开辟新的光谱领域。频率梳技术还通过实现对超快激光脉冲电场的控制，为阿秒科学提供了关键手段。在斯坦福大学和加兴的实验室里，长期以来，开发用于精密激光光谱学的新仪器和新技术的动力，源自于在简单氢原子的光谱学中追求更高分辨率和测量精度的目标，这使得实验与基础理论之间能够进行独特的对比。本次讲座将从我个人的视角讲述这些探索历程以及激光频率梳技术的发展演变。
