Abstract
We demonstrate a versatile new technique that provides a phase coherent link between optical frequencies and the radio frequency domain. The regularly spaced comb of modes of a mode-locked femtosecond laser is used as a precise ruler to measure a large frequency gap between two different multiples (harmonics or subharmonics) of a laser frequency. In this way, we have determined a new value of the hydrogen two-photon resonance, , representing now the most accurate measurement of an optical frequency.
- Received 18 November 1999
DOI:https://doi.org/10.1103/PhysRevLett.84.3232
©2000 American Physical Society
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Letters from the Past - A PRL Retrospective
2008 marked PRL’s 50th anniversary. As part of the celebrations a collection of milestone Letters was started. The collection contains Letters that have made long-lived contributions to physics, either by announcing significant discoveries, or by initiating new areas of research.