Continuous, broad, and single-mode wavelength tuning of thermoelectrically cooled short-pulse quantum-cascade lasers is demonstrated with a combination of coarse grating tuning and fine phase tuning of the gain element. This approach overcomes the problem of a poor facet antireflection coating of the gain chip by shifting a Fabry-Perot longitudinal mode to coincide with the desired grating-selected wavelength. The 9-µm laser was tested with NH3 gas absorption and showed fine frequency tuning at a rate of 31 MHz/step and a time-averaged linewidth of 500–750 MHz. The total tuning range was 9.08–9.36 µm and was limited only by the intrinsic gain of the device.
© 2003 Optical Society of America
Original Manuscript: January 24, 2003
Revised Manuscript: April 26, 2003
Published: August 20, 2003
Chuan Peng, Guipeng Luo, and Han Q. Le, "Broadband, continuous, and fine-tune properties of external-cavity thermoelectric-stabilized mid-infrared quantum-cascade lasers," Appl. Opt. 42, 4877-4882 (2003)