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Searching for applications with a fine-toothed comb



Nathan R. Newbury


Frequency combs, like many ground-breaking technologies, are simple in concept; they results from the spectrum of any regular train of optical pulses. What is remarkable is that this simple picture can be actually realized in a number of different experimental systems. The original application of frequency combs was to compare an optical clock with another rf or optical clock. Such comparisons can reach 10-19 or lower fractional uncertainties, limited only by the Doppler shifts associated with the thermal contraction or expansion of the experimental apparatus [1-3]. However, the utility of frequency combs is not limited to optical clocks; they provide a broadband optical source with well-defined phase coherence across the spectrum and are being explored for a growing number of applications. The variety of applications and approaches are many and this commentary will touch on only a few of the more metrological ones, omitting such significant areas as attosecond laser sources [4]; the reader is directed to some of the many review articles for more details including the 2005 Nobel lectures of Hänsch and Hall [5-8].
Nature Photonics


frequency comb, metrology


Newbury, N. (2011), Searching for applications with a fine-toothed comb, Nature Photonics, [online], (Accessed April 15, 2024)
Created April 1, 2011, Updated December 12, 2017