Mid-IR type-I and type-II quantum cascade lasers

In the past three years, we have been optimizing an alternative cascade configuration based on interband transitions in type-II InAs/InGaSb/AlSb quantum wells (QWs). We have achieved an internal quantum efficiency (IQE) of 580% and a CW output power of 53 mW were achieved at 80 K at 4.4 /spl mu/m. The maximum operation temperature for a 4.2 /spl mu/m type-II IC laser was 220 K with a T/sub 0/ of 285 K around 100 K. A 25-stage interband cascade (IC) laser with a W active region and a third hole quantum well for the suppression of leakage current has exhibited lasing up to 286 K at 3.5 /spl mu/m. We report our most recent results of type-II IC lasers. We also grew 4.6 and a 7.4 /spl mu/m type-I QC laser structures.