Recent advances in quantum cascade laser research and novel applications

Continuous wave (CW) operation of quantum cascade lasers is reported up to a temperature of 312 K. The junction down mounted devices were designed as buried heterostructure lasers with high-reflection coatings on both facets. This resulted in CW operation at an emission wavelength of 9.1μm with an optical power ranging from 17 mW at 293 K to 3 mW at 312 K. A distributed feedback type device was fabricated and tested as well. It showed CW singlemode operation up to 260 K. These results demonstrate the potential of quantum cascade lasers as CW mid-infrared light sources for high-resolution spectroscopy and free space telecommunication systems.