High-Precision Mid-IR Molecular Spectroscopy with Traceability to Primary Standards

We are stabilizing the frequency of a mid-infrared quantum cascade lasers (QCLs) to an optical frequency comb itself stabilized to an ultra-stable near-infrared reference signal at
$\pmb{1.5\mu} \mathbf{m}$
transferred from SYRTE to LPL using an optical link. The reference stability is copied to the QCL and we benefit from the traceability to the primary standards of SYRTE. The stabilized QCL can be scanned by scanning the near-IR reference with an electro-optic modulator. We use this ultrastable spectrometer to carry out saturated absorption spectroscopy of methanol. A detailed analysis of the frequency measurement uncertainty will be presented.