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arXiv · 0804.0955

A laser frequency comb that enables radial velocity measurements with a precision of 1 cm s$^{-1}$

Chih-Hao Li·Andrew J. Benedick·Peter Fendel·Alexander G. Glenday·Franz X. Kaertner·David F. Phillips·Dimitar Sasselov·Andrew Szentgyorgyi·Ronald L. Walsworth
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Abstract

Searches for extrasolar planets using the periodic Doppler shift of stellar spectral lines have recently achieved a precision of 60 cm/s (ref 1), which is sufficient to find a 5-Earth-mass planet in a Mercury-like orbit around a Sun-like star. To find a 1-Earth-mass planet in an Earthlike orbit, a precision of 5 cm/s is necessary. The combination of a laser frequency comb with a Fabry-Perot filtering cavity has been suggested as a promising approach to achieve such Doppler shift resolution via improved spectrograph wavelength calibration, with recent encouraging results. Here we report the fabrication of such a filtered laser comb with up to 40- GHz (1-A) line spacing, generated from a 1- GHz repetition-rate source, without compromising long-term stability, reproducibility or spectral resolution. This wide-line-spacing comb, or `astro-comb', is well matched to the resolving power of high-resolution astrophysical spectrographs. The astro-comb should allow a precision as high as 1 cm/s in astronomical radial velocity measurements.

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Chih-Hao Li, Andrew J. Benedick, Peter Fendel, Alexander G. Glenday, Franz X. Kaertner, David F. Phillips, Dimitar Sasselov, Andrew Szentgyorgyi, Ronald L. Walsworth. 2008-04-07. A laser frequency comb that enables radial velocity measurements with a precision of 1 cm s$^{-1}$. https://doi.org/10.1038/nature06854

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