Toward Stand-Alone Alkali-Based Mid-Infrared Frequency References

Yoel Sebbag, Roy Zektzer, Yefim Barash, Uriel Levy

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Highly accurate and precise spectroscopy in the mid-infrared (MIR) spectral region is a versatile tool that finds great interest in fundamental scientific research as well as in mitigating myriad applications in diverse fields. A major driving force for the rapidly increasing interest in MIR spectroscopy is the emergence of quantum cascade lasers (QCLs). Yet, as of today, such QCLs are still experiencing significant free-running frequency fluctuations which makes their frequency stabilization challenging. Here, we propose and experimentally demonstrate a method enabling development of frequency standards in the MIR, based on high excited stats of alkali vapors. The technique is based on the generation of a Doppler-free gain spectrum in the MIR by copropagating two stabilized pump near-infrared (NIR) lasers. Using this technique, the frequency of a distributed feedback (DFB) QCL at 5.23 μm is stabilized to the corresponding 62P3/2-52D5/2 transition of rubidium (Rb) vapors, showing a substantial stability improvement compared to the free-running operation. Stabilization to an atomic MIR transition can be implemented in a rather simple scheme, with diverse applications. For example, the approach may enable the development of highly accurate self-calibrated optical spectrometers and can also be used for direct stabilization of MIR frequency combs.

Original languageAmerican English
Pages (from-to)1508-1514
Number of pages7
JournalACS Photonics
Issue number6
StatePublished - 17 Jun 2020

Bibliographical note

Publisher Copyright:
Copyright © 2020 American Chemical Society.


  • atoms
  • metrology
  • mid-infrared spectroscopy
  • quantum cascade lasers


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