Towards high-performance injectorless quantum cascade lasers in the mid infrared

Lately injectorless quantum cascade lasers are getting more and more into focus of research, as they promise lower threshold current densities and higher output powers and efficiencies. Although the research on them started seven years later in 2001 and was less intensive, they have achieved much lower threshold current densities with 0.45 kA/cm² at 300 K compared to injectorbased devices. Additionally injectorless devices reached efficiencies and output powers in the important wavelength range between 8 and 12 μm comparable to best performing injectorbased devices. With 2 W per facet and an overall efficiency of 7 % around 9 μm, they show a strong potential regarding possible applications.