Free-running 9.1-microm distributed-feedback quantum cascade laser linewidth measurement by heterodyning with a C18O2 laser.
We report spectral linewidth measurements of a 9.1-microm distributed-feedback quantum cascade laser (QCL). The free-running QCL beam was mixed with a waveguide isotopic C18O2 laser onto a high-speed HgCdTe photomixer, and beat notes were recorded from a radio-frequency spectral analyzer. Beating was performed at two operating conditions, first near the QCL laser threshold (beating with the C18O2 R10 line) and then at a high injection current (beating with the C18O2 R8 line). Overall, beat note widths of 1.3-6.5 MHz were observed, which proves that a free-running QCL can have a short-term spectral width near 1 MHz.
Groupe de Spectroscopie Moléculaire et Atmosphérique, Faculté des Sciences, Université de Reims Champagne-Ardenne, BP 1039, 521687 Reims Cedex 2, France. damien.weidmann@univ-reims.fr
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D
Weidmann
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Joly
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V
Parpillon
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Courtois
Y
Y
Bonetti
T
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Aellen
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Beck
J
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Faist
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Hofstetter