Berlin 2001 – wissenschaftliches Programm

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Q: Quantenoptik

Q 19: Laser I

Q 19.6: Vortrag

Mittwoch, 4. April 2001, 17:00–17:15, H 1012

Characterisation of a mid-infrared (5 µm) Quantum Cascade Laser — •H. Ganser¹, D. Halmer², M. Mürtz¹, P. Hering¹, C. Gmachl³, F. Capasso³, D. Sivco³, J. Baillargeon³, A. Hutchinson³, A. Cho³, and W. Urban² — ¹Institut für Lasermedizin, Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf — ²Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, 53115 Bonn — ³Bell Laboratories, Lucent Technologies, 600 Mountain Avenue, Murray Hill, NJ 07974, USA

The quantum cascade laser (QCL) is a new source of coherent light in the mid-infrared spectral region. It combines high output power (up to 10 mW in cw mode at liquid nitrogen temperatures) with continuous tunability and narrow linewidth. We applied a QCL provided by the Bell Labs covering cw a frequency range of 1912 to 1922 wavenumbers (5.2 µm). The laser has been applied for a sensitive nitrogen oxide detection via a dispersion technique called Faraday Rotation Spectroscopy. This technique requires a narrow linewidth in the order of some MHz. We performed beat experiments between a distributed feedback QCL and a CO laser and determined the passive cw linewidth to be less than one MHz. The main point in reaching this stability of the laser was to get a sufficiently stable current source with a relative voltage stability of 5 × 10⁻⁷. This project was supported by the DFG through SFB 334.