Growth of GaAs based quantum cascade lasers

Quantum cascade lasers (QCLs) based on intersubband/interminiband transitions in InGaAs/InAlAs/InP and GaAs/AlGaAs are unipolar intraband semiconductor lasers. Their wavelength can be tailored over a wide range of frequencies by adapting layer thicknesses of the same material. We report about our latest improvements in the realisation of GaAs based quantum cascade lasers. Intersubband transitions in coupled quantum wells and intraband transitions in a finite chirped superlattice are used to demonstrate lasing.