Abstract
We report on the development of strain compensated InGaAs/AlAs(Sb) quantum cascade lasers, incorporating a buried third order distributed feedback grating. Single mode operation with a side mode suppression ratio of similar to 30 dB has been achieved in the wavelength range of 3.358-3.380 mu m for temperatures between 270 and 360 K. The threefold increase in grating pitch size, compared with a first order grating, allows conventional photolithographic techniques to be used for single mode laser fabrication. (C) 2010 American Institute of Physics. [doi:10.1063/1.3487781]