Contributions to the large blue emission shift in a GaAsSb type-II laser

The large blue shift in the emission with excitation in a GaAsSb-based type-II quantum well is investigated experimentally and theoretically. Comparison of theory with experiment is made for lasers with "W" type-II structures. The analysis shows the blue shift to be the result of charge-separation, band-distortion, and many-body interactions. For a high threshold gain, there is an additional contribution from the n=2 subband transition.