High-performance continuous wave type-II interband cascade lasers

Interband cascade (IC) lasers that utilize optical transitions between the conduction and valence bands in staircase of Sb-based type-II quantum wells (QWs) represent a new class of mid-infrared (IR) diode lasers. IC lasers reuse injected electrons by taking advantage of the broken gap alignment in Sb-based type-II QWs to form cascade stages, leading to a quantum efficiency greater than the conventional limit of unity, similar to the intersubband quantum cascade (QC) laser. Furthermore, IC laser designs can circumvent the fast phonon scattering loss in intersubband QC lasers and suppress Auger recombination through band-structure engineering, leading to lower threshold currents and more efficient operation. Significant advances in the development of type-II IC lasers (/spl lambda//spl sim/3.9 /spl mu/m) were made recently by us at ARL in terms of record-high differential external quantum efficiency (DEQE) (/spl sim/500%), peak output power (>4 W/facet), peak power conversion (wall-plug) efficiency (/spl sim/7%), and reproducibility. We report our most recent progress in achieving high-performance mid-infrared (/spl sim/3.7 /spl mu/m) type-II IC lasers under continuous-wave conditions.