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Coherently-averaged dual comb spectrometer at 7.7 µm with master and follower quantum cascade lasers

Kenichi Komagata, Atif Shehzad, Giulio Terrasanta, Pierre Brochard, Renaud Matthey-De-L'Endroit, Michele Gianella, Pierre Jouy, Filippos Kapsalidis, Mehran Shahmohammadi Mehran, Matthias Beck Matthias, Valentin Wittwer, Jérôme Faist, Lukas Emmenegger, Thomas Südmeyer, Andreas Hugi & Stephane Schilt

Résumé We demonstrate coherent averaging of the multi-heterodyne beat signal between two quantum cascade laser frequency combs in a master-follower configuration. The two combs are mutually locked by acting on the drive current to control their relative offset frequency and by radio-frequency extraction and injection locking of their intermode beat signal to stabilize their mode spacing difference. By implementing an analog common-noise subtraction scheme, a reduction of the linewidth of all heterodyne beat notes by five orders of magnitude is achieved compared to the free-running lasers. We compare stabilization and post-processing corrections in terms of amplitude noise. While they give similar performances in terms of signal-to-noise ratio, real-time processing of the stabilized signal is less demanding in terms of computational power. Lastly, a proof-of-principle spectroscopic measurement was performed, showing the possibility to reduce the amount of data to be processed by three orders of magnitude, compared to the free-running system.
   
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Citation Komagata, K., Shehzad, A. ., Terrasanta, G., Brochard, P., Matthey-De-L'Endroit, R., Gianella, M., Jouy, P., Kapsalidis, F. ., Shahmohammadi Mehran, M., Beck Matthias, M., Wittwer, V., Faist, J., Emmenegger, L., Südmeyer, T., Hugi, A., & Schilt, S. (2021). Coherently-averaged dual comb spectrometer at 7.7 µm with master and follower quantum cascade lasers. Optics Express, 29(12), 19126-19139.
   
Type Article de périodique (Anglais)
Date de publication 6-2021
Nom du périodique Optics Express
Volume 29
Numéro 12
Pages 19126-19139
URL https://doi.org/10.1364/OE.425480