Room temperature quantum cascade lasers with 27% wall plug efficiency

Using the recently proposed shallow-well design, we demonstrate InP based quantum cascade lasers (QCLs) emitting around 4.9 mu m with 27% and 21% wall plug efficiencies in room temperature (298 K) pulsed and continuous wave (cw) operations, respectively. The laser core consists of 40 QCL-stages. The highest cw efficiency is obtained from a buried-ridge device with a ridge width of 8 mu m and a cavity length of 5 mm. The front and back facets are antireflection and high-reflection coated, respectively. The maximum single facet cw power at room temperature amounts to 5.1 W. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3586773]