Mid-IR frequency measurement using an optical frequency comb and a   long-distance remote frequency reference
  We have built a frequency chain which enables to measure the absolute frequency of a laser emitting in the 28-31 THz frequency range and stabilized onto a molecular absorption line. The set-up uses an optical frequency comb and an ultrastable 1.55 $\mu$m frequency reference signal, transferred from LNE-SYRTE to LPL through an optical link. We are now progressing towards the stabilization of the mid-IR laser via the frequency comb and the extension of this technique to quantum cascade lasers. Such a development is very challenging for ultrahigh resolution molecular spectroscopy and fundamental tests of physics with molecules. 
Bruno Chanteau (LPL), Olivier Lopez (LPL), Wei Zhang (SYRTE), Giorgio   Santarelli (SYRTE, LP2N), Yann Le Coq (SYRTE), Fr\'e...
physics.atom-ph physics.optics quant-ph