Absolute optical frequency measurements of iodine-stabilized He-Ne laser at 633 nm by using a femtosecond laser frequency comb

Spanish Centre of Metrology, Length Area, C/ del Alfar 2, Tres Cantos 28760 Madrid, Spain

^⋆ Correspondence: bsamoudi@cem.minetur.es

Received: 5 May 2012
Accepted: 15 June 2012

Abstract

The optical frequency comb generator (OFCG) is an attractive optical reference source for various applications such as optical frequency metrology, precision spectroscopy and telecommunications [D.J. Jones, S.A. Diddams, J.K. Ranka, A. Stentz, R.S. Windeler, S.T. Cundiff, Science 288, 635–639 (2000); T. Udem, R. Holzwarth, T.W. Hänsch, Nature 416, 233–237 (2002); T.W. Hänsch, J. Alnis, P. Fendel, M. Fischer, C. Gohle, M. Herrmann, R. Holzwarth, N. Kolachevsky, Th. Udem, M. Zimmermann, Philos. Trans. R. Soc. A 363, 2155–2163 (2005)]. In particular, the OFCG can be used as source for absolute frequency measurement, providing a precise ruler for length metrology. In the present work we describe the results of absolute frequency measurements of primary wavelength standards at 633 nm on the sixth components, d, e, f, g, h and i of the R(127) 11-5 hyperfine transition of the ¹²⁷I₂ molecule, at the Spanish Centre of Metrology, CEM. The values obtained with a femtosecond frequency comb (FC1500, Menlo Systems) at CEM are compared with the values recommended by the Consultative Committee for Length (CCL) [T.J. Quinn, Metrologia 40, 103–133 (2003)]. This determination was made by beat frequency method between a femtosecond laser comb and an iodine-stabilized He-Ne laser. The difference between the mean frequency of the sixth components of the standard laser and those of CCL recommended values for the same components was found to be 6.557 kHz.