International Comparisons of Femtosecond Laser Frequency Combs

Published

April 1, 2005

Author(s)

Long-Sheng Ma, Zhiyi Bi, A Bartels, Lennart Robertsson, Massimo Zucco, Robert Windeler, G Wilpers, Christopher W. Oates, Leo W. Hollberg, Scott A. Diddams

Abstract

Two types of international comparisons of femtosecond laser frequency combs have been performed in France and the USA. Five combs were involved in the comparisons. Three combs, of which two are transportable, employ nonlinear photonic crystal fiber (PCF) to obtain a wide spectrum covering a full optical octave. The other two are based on broadband femtosecond lasers and require no PCF. The comparisons were performed by counting the optical heterodyne beats between pairs of combs. The frequency agreement among three combs was at the subhertz level in the 563 THz part of the comb spectrum when the combs were referenced to a hydrogen maser. When the combs were referenced to an optical standard, the frequency agreement among four combs was much improved and found to be at the ~ 10^-19 level in the spectral range of 333?473 THz. The fact that this result is obtained by five independent measurement systems (combs) strengthens the conclusion that no systematic effects are present at this level.

Citation

IEEE Transactions on Instrumentation and Measurement

Volume

54

Issue

2

Pub Type

Journals

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Keywords

femtosecond laser, frequency measurement, frequency standards

Citation

Ma, L. , Bi, Z. , Bartels, A. , Robertsson, L. , Zucco, M. , Windeler, R. , Wilpers, G. , Oates, C. , Hollberg, L. and Diddams, S. (2005), International Comparisons of Femtosecond Laser Frequency Combs, IEEE Transactions on Instrumentation and Measurement, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=50123 (Accessed November 3, 2025)