Optimization of the active region of interband cascade lasers emitting in the MIR

Interband cascade lasers (ICLs) are efficient mid-infrared (MIR) semiconductor light sources based typically on InAs and GaInSb materials forming a broken gap system and hence type II quantum wells (QWs) being the active part in this kind of emitters. There has already been achieved a significant progress in the performance of ICLs, driven mainly by the gas sensing applications and originating from their unique operational characteristics when especially compared to quantum cascade lasers. However, there are still growing demands with respect to laser sources in the MIR and new areas of applications evolve, all of which stimulate the efforts to improve the performance of such devices and to search for completely new solutions which could offer properties hardly reachable with existing structures. Here, by using k·p theory employing strain and band structure engineering of various In(As,Sb) and (Ga,In)(As,Sb) type II materials’ combinations there will be considered several novel designs of the active region of ICLs. These calculations show that such new features can be obtained as fully strain-free ICL devices, significant extension of the emission spectral range, polarization independent gain in the MIR or enhanced sensitivity of radiative processes rates to external electric field to be exploited in bias-controlled mode-locked ICLs. The respective type II QW designs are proposed and discussed.