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Published July 17, 2020 | public
Journal Article

Optical frequency combs: Coherently uniting the electromagnetic spectrum


Optical clocks, based on optical transitions of atoms, operate at much higher frequency than the microwave atomic clocks currently used as our timing standards. They have been shown to exhibit better stability and are poised to redefine the second. The development of stable, self-referenced optical frequency combs that span the microwave to optical wavelengths has been key to these efforts. Diddams et al. reviewed developments and refinements of these optical combs over the past 20 years and provide an overview of where they are finding application, from precision timing to high-resolution spectroscopy and imaging, ranging, and navigation.

Additional Information

© 2020 American Association for the Advancement of Science. This is an article distributed under the terms of the Science Journals Default License. We are grateful to T. Hänsch and J. Hall for their input, vision, and leadership in this field, as well as to N. Newbury, C. Oates, and J. Ye for their comments on this manuscript. We also thank B. Baxley, T. Briles, J. Knight, S. Papp, P. Russell, R. Windeler, and the University of Bath for their contributions to the figures. Finally, we are indebted to the many colleagues with whom we have had the privilege to learn about the ever-expanding field of optical frequency combs. Funding: This material is based on work supported by the National Institute of Standards and Technology (NIST); the Defense Advanced Research Projects Agency (DARPA) under awards in the DODOS (HROO1 1-15-C-0055), APHi (FA9453-19-C-0029), SCOUT (W31P4Q-15-1-0011), and ACES programs; and the Air Force Office of Scientific Research (AFOSR) under awards FA9550-16-1-0016 and FA9550-18-1-0353. Competing interests: T.U. is an inventor on patents US6785303B1 and US20060268949 held by the Max-Planck-Gesellschaft zur Förderung der Wissenschaften that cover optical frequency combs.

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August 19, 2023
October 20, 2023