Faculté des sciences

Free-running 9.1-μm distributed-feedback quantum cascade laser linewidth measurement by heterodyning with a C18O2 laser

Weidmann, D. ; Joly, L. ; Parpillon, V. ; Courtois, D. ; Bonetti, Yargo ; Aellen, Thierry ; Beck, Mattias ; Faist, Jérôme ; Hofstetter, Daniel

In: Optics Letters, 2003, vol. 28, no. 9, p. 704-706

We report spectral linewidth measurements of a 9.1-μm 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... Plus

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    Summary
    We report spectral linewidth measurements of a 9.1-μm 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 C18O2R10 line) and then at a high injection current (beating with the C18O2R8 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.