Open AccessCoherently-averaged dual comb spectrometer at 7.7 µm with master and follower quantum cascade lasers
Author(s) -
Kenichi Komagata,
Atif Shehzad,
Giulio Terrasanta,
Pierre Brochard,
Renaud Matthey,
Michele Gianella,
Pierre Jouy,
Filippos Kapsalidis,
Mehran Shahmohammadi,
Mattias Beck,
Valentin J. Wittwer,
Jérôme Faist,
Lukas Emmenegger,
Thomas Südmeyer,
Andreas Hugi,
Stéphane Schilt
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.425480
Subject(s) - optics , cascade , beat (acoustics) , physics , laser linewidth , quantum cascade laser , laser , heterodyne detection , frequency offset , computer science , telecommunications , channel (broadcasting) , chemistry , chromatography , orthogonal frequency division multiplexing
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.