Merging the Ultrasensitive the Ultrastable, and the Ultrafast: A New Epoch of Frequency Standards and Optical Frequency Measurement
John L. Hall, Jun Ye
The use of optical frequencies in measurement science has been proposed and practiced since the very early days of the invention of lasers. Comparison of a laser frequency at some 5 x 1014 Hz with its ideal few-milliHertz linewidth produced by the fundamental phase diffusion of spontaneous emissions reveals a potential dynamic range of 1017 in resolution, offering one of our best toos for discovering new physics, in just the next decimal. Nearly forty years of vigorous research in the many diverse aspects of this field by a world-wide community have resulted in exciting discoveries in fundamental science and development of enabling new technologies. Some of the ambitious long-term goals in optical frequency metrology are just coming to fruition owing to a number of recently achieved spectacular technological advances. A few examples include laser frequency stabilization to one Hz and below, optical transitions observed at a few Hz linewidth (corresponding to a Q of 1.5 x 1014), accuracy level of optical standards steadily improving with a potential target of 10-18 based on cold atom/ion systems, and a direct phase coherent link between microwave and any portion of the optical spectrum. Indeed, it now seems to be quite feasible to ralize, within a reasonable degree of simplicity and yet robustness, an optical-based atomic clock and an optical frequency synthesizer. Considering that most modern measurement experiments are characterized by their use of frequency-based metrology, one can foresee a tremendous growth of activities in these related research fields.
and Ye, J.
Merging the Ultrasensitive the Ultrastable, and the Ultrafast: A New Epoch of Frequency Standards and Optical Frequency Measurement, Optics and Photonics News
(Accessed March 1, 2024)