| Issue |
EPJ Web Conf.
Volume 362, 2026
31st International Laser Radar Conference (ILRC 31) Held Together with the 22nd Coherent Laser Radar Conference (CLRC 22)
|
|
|---|---|---|
| Article Number | 13002 | |
| Number of page(s) | 4 | |
| Section | CLRC Coherent Sensing Modalities and Architectures | |
| DOI | https://doi.org/10.1051/epjconf/202636213002 | |
| Published online | 09 April 2026 | |
https://doi.org/10.1051/epjconf/202636213002
Long-wave infrared FMCW ranging systems based on external coherent detection and self-mixing interferometry
(a) Thales SIX France 4, Av. des Louvresses, 92230 Gennevilliers, FRANCE
(b) Laboratoire de Physique de l'Ecole Normale Supérieure 24 rue Lhommond, 75005 Paris, France
(c) Thales Research and Technology 1, Av. Augustin Fresnel, 91120 Palaiseau, France
Published online: 9 April 2026
Abstract
Long-wave infrared (LWIR) wavelengths are expected to provide a better robustness against meteorological perturbations as well as an increased covertness for hard target FMCW LiDAR. However, the implementation and modulation of LWIR sources and detectors constitutes an important challenge. With a custom quantum cascade detector, we demonstrate for the first time a QCL-based FMCW ranging system up to 50 m on an outdoor static target, with a < 2 % relative precision. It relies on the linear optical frequency modulation of the QCL, up to 8.4 GHz in 65 µs with 0.03 % of nonlinearities. Furthermore, through a novel method of self-mixing interferometry, we exploit the laser perturbations caused by optical feedback to perform FMCW ranging with fewer components. Similar results are obtained with both architectures, opening the way to low-complexity LWIR FMCW systems, where the low maturity of optical isolators and components makes it a critical asset.
© The Authors, published by EDP Sciences, 2026
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