Abstract

We report experiments evaluating the feasibility of quantum-cascade lasers (QCLs) at mid-infrared wavelengths for use as local oscillators (LOs) in a heterodyne receiver. Performance tests with continuous-wave (cw) lasers around 9.6 and 9.2 µm were carried out investigating optical output power, laser linewidth, and tunability. A direct comparison with a CO₂ gas laser LO is presented as well. The achieved system sensitivity in a heterodyne spectrometer of only a factor of 2 above the quantum limit together with the measured linewidth of less than 1.5 MHz shows that QCLs are suitable laser sources for heterodyne spectroscopy with sufficient output power to replace gas lasers as LOs even in high-sensitivity astronomical heterodyne receivers. In addition, our experiments show that the tunability of the lasers can be greatly enhanced by use of an external cavity.

© 2005 Optical Society of America

Fully reflective external-cavity setup for quantum-cascade lasers as a local oscillator in mid-infrared wavelength heterodyne spectroscopy

Dušan Stupar, Jürgen Krieg, Peter Krötz, Guido Sonnabend, Manuela Sornig, Thomas F. Giesen, and Rudolf Schieder
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Terahertz quantum cascade laser as local oscillator in a heterodyne receiver

H.-W. Hübers, S. G. Pavlov, A. D. Semenov, R. Köhler, L. Mahler, A. Tredicucci, H. E. Beere, D. A. Ritchie, and E. H. Linfield
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High-sensitivity mid-infrared heterodyne spectrometer with a tunable diode laser as a local oscillator

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Phase locking of a 1.5 Terahertz quantum cascade laser and use as a local oscillator in a heterodyne HEB receiver

D. Rabanus, U. U. Graf, M. Philipp, O. Ricken, J. Stutzki, B. Vowinkel, M. C. Wiedner, C. Walther, M. Fischer, and J. Faist
Opt. Express 17(3) 1159-1168 (2009)

Tuneable Heterodyne Infrared Spectrometer for atmospheric and astronomical studies

Guido Sonnabend, Daniel Wirtz, Frank Schmülling, and Rudolf Schieder
Appl. Opt. 41(15) 2978-2984 (2002)