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Frequency stability of a dual wavelength quantum cascade laser
Auteur(s)
Sargachev, Ilia
Maulini, Richard
Gresch, Tobias
Blaser, Stéphane
Bismuto, Alfredo
Müller, Antoine
Bidaux, Yves
In
Optics Express, Optical Society of America, 2017/25/10/11027-11037
Résumé
We characterized the dual wavelength operation of a distributed Bragg reflector (DBR) quantum cascade laser (QCL) operating at 4.5 μm using two independent optical frequency discriminators. The QCL emits up to 150 mW fairly evenly distributed between two adjacent Fabry-Perot modes separated by ≈11.6 GHz. We show a strong correlation between the instantaneous optical frequencies of the two lasing modes, characterized by a Pearson correlation coefficient of 0.96. As a result, we stabilized one laser mode of the QCL to a N<sub>2</sub>O transition using a side-of-fringe locking technique, reducing its linewidth by a factor 6.2, from 406 kHz in free-running operation down to 65 kHz (at 1-ms observation time), and observed a simultaneous reduction of the frequency fluctuations of the second mode by a similar amount, resulting in a linewidth narrowing by a factor 5.4, from 380 kHz to 70 kHz. This proof-of-principle demonstration was performed with a standard DBR QCL that was not deliberately designed for dual-mode operation. These promising results open the door to the fabrication of more flexible dual-mode QCLs with the use of specifically designed gratings in the future.
Identifiants
Type de publication
journal article
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