Single-frequency operation of a 10.4-μm room-temperature multimode quantum-cascade laser was achieved by use of a 17-mm short Littrow-type external-cavity configuration. The spectral intensity of the external-cavity laser was increased as much as 20-fold compared with that of a multimode quantum-cascade laser without an external cavity. A single-frequency tuning range of 76 nm (7 cm<sup>-1</sup>) was achieved. The results were obtained without antireflection coating of the laser output facet.
© 2002 Optical Society of America
(140.3070) Lasers and laser optics : Infrared and far-infrared lasers
(140.3570) Lasers and laser optics : Lasers, single-mode
(140.3600) Lasers and laser optics : Lasers, tunable
(140.4780) Lasers and laser optics : Optical resonators
(140.5960) Lasers and laser optics : Semiconductor lasers
G. Totschnig, F. Winter, V. Pustogov, J. Faist, and A. Müller, "Mid-infrared external-cavity quantum-cascade laser," Opt. Lett. 27, 1788-1790 (2002)