Fully reflective external-cavity setup for quantum-cascade lasers as a local oscillator in mid-infrared wavelength heterodyne spectroscopy.
To our knowledge we present the first experiments with a fully reflective external-cavity quantum-cascade laser system at mid-infrared wavelengths for use as a local oscillator in a heterodyne receiver. The performance of the presented setup was investigated using absorption spectroscopy as well as heterodyne techniques. Tunability over approximately 30 cm(-1) at 1130 cm(-1) was demonstrated using a grating spectrometer. A continuous tuning range of 0.28 cm(-1) was verified by observing the spectra of an internally coupled confocal Fabry-Pérot interferometer and the absorption lines of gas phase SO(2). In a second step the output from the system was used as a local oscillator signal for a heterodyne setup. We show that spectral stability and side mode suppression are excellent and that a compact external-cavity quantum-cascade laser system is well suited to be used as a local oscillator in infrared heterodyne spectrometers.
Stupar
Dusan
D
Physikalisches Institut, Universitat zu Koln, Zulpicher Strasse, Koln, Germany. supar@ph1.uni-koeln.de
Krieg
Jürgen
J
Krötz
Peter
P
Sonnabend
Guido
G
Sornig
Manuela
M
Giesen
Thomas F
TF
Schieder
Rudolf
R