High-brightness from unstable resonator mid-IR semiconductor lasers

We describe high-brightness, broad area midinfrared semiconductor lasers. The laser structures incorporated 14 type-II quantum wells imbedded in thick waveguide/absorber regions composed of InGaAsSb. The optically pumped devices achieved higher brightness operation as unstable facets. For a 4 mm UR operating at λ = 4.7μm and at 35 × threshold the device was observed to be diffraction limited. In comparison a standard Fabry-Perot laser was many times diffraction limited.