Mid-IR frequency measurement using an optical frequency comb and a long-distance remote frequency reference

TL;DR

This paper presents a method for precise mid-infrared laser frequency measurement using an optical frequency comb and a remote ultrastable frequency reference, enabling advanced molecular spectroscopy and fundamental physics tests.

Contribution

The authors developed a frequency chain that measures and stabilizes mid-IR lasers using an optical comb and remote frequency reference, extending to quantum cascade lasers.

Findings

Successful measurement of laser frequencies in the 28-31 THz range.

Implementation of remote ultrastable frequency transfer.

Progress towards stabilizing mid-IR lasers for high-resolution spectroscopy.

Abstract

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.