The team

Membres : Anne Amy-Klein, Benoît Darquié, Mathieu Manceau, Olivier Lopez

PhD students : Yuhao Liu, Sahil Viel
Postdocs : Minh Nhut Ngo,

Former members : Sean Tokunaga (maître de conférences), Dang Bao An Tran (doctorant), Nicolas Cahuzac (doctorant).

Research activities

For the past twelve years, we have been developing a system that enables the measurement of the absolute frequency of molecular transitions in the mid-infrared (MIR) or visible range, with a resolution (at 1 s) and accuracy better than a few 10^−14. This system is based on the use of a femtosecond pulse laser as a frequency comb. The measurement uncertainty is directly linked to the frequency reference used to control the repetition rate of the frequency comb.

Recently, a more reliable and higher-performance system was rebuilt using a new frequency comb operating around 1.55 µm. Thanks to the latest developments in optical links, we can lock this comb to an optical frequency reference developed at SYRTE, whose absolute frequency is controlled by their primary frequency standards. This reference is transferred via an optical link to LPL and allows us to control the frequency of an MIR laser with our frequency comb. We achieve this through a nonlinear frequency mixing setup, which generates a beat note between a high harmonic of the comb’s repetition rate and the MIR laser. The frequency of the MIR laser is thus known with a maximum uncertainty on the order of 10⁻¹⁴ over a 100 s measurement time.

This system was initially developed with CO₂ lasers emitting around 30 THz, and we later extended it to quantum cascade lasers (QCLs). The latter are inherently noisier and therefore more difficult to stabilize, but we successfully demonstrated the same stability performance (a few 10⁻¹⁴over a 1 s measurement time) and achieved a record linewidth of less than 1 Hz. We are currently developing a frequency scanning system for the comb, which should enable the stabilized QCL to be continuously tuned over more than 1 GHz for molecular spectroscopy applications.

Through this project, we demonstrated that the ultrastable signal transferred via optical link is a reliable and efficient source for frequency stabilization of a wide range of lasers, thereby eliminating the need for local frequency stabilization systems. This is one of the very first applications of optical links and frequency combs beyond the field of metrology. This system paves the way for ultra-high-sensitivity experiments on molecules, reaching the same precision level as those conducted with atoms.

News

Available Positions

We are currently looking for an M2 student for an internship in spring 2025 that could be followed by a PhD thesis : see Offer

Collaborations

Time-Frequency Metrology

Ultra-stable signal
Frequency standards
Stabilized fiber link

Mid-IR photonics

Mid-IR electro-optics modulators
Mid-IR detectors
QCLs

Funding

We acknowledge the support from various funding agencies :

ANR BIRD
ANR CORALI

Publications

2025

2024

M. Saemian et al., Ultra-sensitive heterodyne detection at room temperature in the atmospheric windows.
Nanophotonics 8 (2024).
D. B. A. Tran et al., Near-to mid-IR spectral purity transfer with a tunable frequency comb: Methanol frequency metrology over a 1.4 GHz span.
APL Photonics 9 (2024).

2023

B. Chomet et al., Highly coherent phase-lock of an 8.1 μm quantum cascade laser to a turn-key mid-IR frequency comb.
Applied Physics Letters 122 (2023).
H. Dely et al., Heterodyne coherent detection of phase modulation in a mid-infrared unipolar device.
Optics Express 31, 30876–30883 (2023).

2010 – 2020

B. Argence, B. Chanteau, O. Lopez, D. Nicolodi, M. Abgrall, C. Chardonnet, C. Daussy, B. Darquié, Y. Le Coq and A. Amy-Klein,
Quantum cascade laser frequency stabilization at the sub-Hz level,
Nature Photonics (2015).
PLT Sow, S Mejri, SK Tokunaga, O Lopez, A Goncharov, B Argence, C Chardonnet, A Amy-Klein, C Daussy and B Darquié, A widely tunable 10-µm quantum cascade laser phase-locked to a state-of-the-art mid-infrared reference for precision molecular spectroscopy,
App. Phys. Lett. 104, 264101 (2014); arXiv
B. Chanteau, O. Lopez, W. Zhang, D. Nicolodi, B. Argence, F. Auguste, M. Abgrall, C. Chardonnet, G. Santarelli, B. Darquié, Y. Le Coq and A. Amy-Klein,
Mid-infrared laser phase-locking to a remote near-infrared frequency reference for high precision molecular spectroscopy,
New J. Phys. 15, 073003 (2013).

Thesis

N. Cahuzac, Lasers à cascade quantique moyen infrarouges stabilisés sur des peignes de fréquences avec traçabilité au SI : application à la spectroscopie de haute précision du méthanol et de l’ozone.
Thèse de doctorat, Université Sorbonne Paris Nord, 2023.
D. B. A. Tran, Widely tunable and SI-traceable frequency-comb-stabilised mid-infrared quantum cascade laser: application to high precision spectroscopic measurements of polyatomic molecules.
PhD Thesis, Université Paris 13, 2019.
B. Chanteau, Transfert à très haute résolution d’une référence de réquence ultra-stable par lien optique et application à la stabilisation d’un laser moyen-infrarouge.
Thèse de doctorat, Université Paris-Nord-Paris 13, 2013.