Mid-infrared type-II interband cascade lasers

Interband cascade (IC) lasers that utilize optical transitions between the conduction and valence bands in a staircase of Sb-based type-II quantum wells (QWs) represent a new class of mid-IR diode lasers. By combining the advantages of quantum cascade lasers and type-II QW interband lasers, type-II IC lasers show promise of operating in continuous-wave (CW) mode up to room temperature with high output powers. Significant advances toward such high performance have been reported in terms of record-high differential external quantum efficiency (DEQE>600%), peak output power (~6 W/facet at 80 K), CW power conversion efficiency (>16% at 80 K), and room-temperature operation under pulsed conditions. Here, we will review the progress made in the past few years and discuss the issues encountered during the development. Also, the current status of type-II IC lasers and the remaining challenges will be discussed