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Frequency comb spectroscopy

Abstract

A laser frequency comb is a broad spectrum composed of equidistant narrow lines. Initially invented for frequency metrology, such combs enable new approaches to spectroscopy over broad spectral bandwidths, of particular relevance to molecules. The performance of existing spectrometers — such as crossed dispersers employing, for example, virtual imaging phase array étalons, or Michelson-based Fourier transform interferometers — can be dramatically enhanced with optical frequency combs. A new class of instruments, such as dual-comb spectrometers without moving parts, enables fast and accurate measurements over broad spectral ranges. The direct self-calibration of the frequency scale of the spectra within the accuracy of an atomic clock and the negligible contribution of the instrumental line-shape will enable determinations of all spectral parameters with high accuracy for stringent comparisons with theories in atomic and molecular physics. Chip-scale frequency comb spectrometers promise integrated devices for real-time sensing in analytical chemistry and biomedicine. This Review gives a summary of the developments in the emerging and rapidly advancing field of atomic and molecular broadband spectroscopy with frequency combs.

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Support by the Carl-Friedrich-von-Siemens Foundation is gratefully acknowledged.

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Correspondence to Nathalie Picqué.

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Further reading

Fig. 1: Principle of a frequency comb and sketch of a simple experiment of frequency comb spectroscopy.
Fig. 2: Spectral coverage with a selection of sources available for frequency comb spectroscopy.
Fig. 3: Spectrometric techniques for frequency comb spectroscopy.
Fig. 4: Physical principle of some of the described spectrometric techniques.
Fig. 5: Illustration of experimental results from the different approaches to frequency comb spectroscopy.
Fig. 6: Spectral coverage of dual-comb spectroscopy.