GaAs-AlGaAs based micro lasers emitting at 10 /spl mu/m and 13 /spl mu/m

The unipolar semiconductor lasers presented here are quantum cascade lasers (QCL). The lasing transition of the first QCLs occurs between 2 intersubband levels of 3-coupled quantum wells. Electrons are injected into the intersubband levels over a specially designed non-periodic superlattice. One period, consisting of injector and coupled quantum wells is repeated typically 30 times and acts as gain region. Besides coupled quantum wells a periodic or chirped superlattice can act as gain medium. In these miniband lasers the radiative transition takes place between two minibands of a periodic superlattice.