High power quantum cascade lasers operating at room temperature

In this paper, some key design and technology issues for development of high power quantum cascade lasers are discussed. The scaling of power output with the number of emitting stages is shown. As part of this work, high power, 75-stage, lambda = 9 mum lasers have been demonstrated with a peak power of 7 W at room temperature. This power is a direct result of high quality material growth and a low loss waveguide design. Similar results are demonstrated at a shorter wavelength (lambda = 6.1 mum) utilizing a strain-balanced active region/injector design. For a 30-stage structure, 2 W peak power and 250 mW average power have been demonstrated at room temperature. Lastly, a timeline comparison of QCL laser performance is presented in terms of room temperature threshold current density and peak output power for various groups.