Abstract
We review the recent development of high-performance short-wavelength (lambda similar to 3.05-3.8 mu m) strain-compensated InGaAs/AlAs(Sb)/InP quantum cascade lasers (QCLs). The lasers are demonstrated in which wavelengths as low as 3.05 mu m are obtained at temperatures up to 295 K. We also verify that strain-compensated In0.7Ga0.3As/AlAs(Sb) QCLs with AlAs barriers in the active region operate with much better performance compared with the lasers having identical design but with AlAsSb barriers throughout the whole core region. lambda similar to 3.3-3.7 mu m laser emission is observed at temperatures up to at least 400 K and up to 20 W of output optical power at 285 K for the QCLs with various core region designs. Room temperature distributed feedback InGaAs/AlAs(Sb) QCLs with buried third-order gratings have been also developed, displaying single-mode operation in the wavelength range of 3.358-3.380 mu m for temperatures between 270 and 360 K.