The antiguiding parameter in mid-infrared optically pumped semiconductor lasers

We describe measurements of the antiguiding parameter, α, for several optically pumped semiconductor lasers. The two W lasers, incorporated 14 type-II quantum wells (QWs) and operated at wavelengths of ~3.5 and ~4.5 μm. The lasers displayed low antiguiding factors of ~1.0. We attribute the low α's for the W lasers to the higher QW gain as well as to inhomogeneous broadening induced by the 14 QWs. The differing well widths and the independent optical pumping of the wells, leads to a net gain spectrum that is symmetrical about the gain peak. This symmetry, in turn, leads to small differential index shifts at the gain peak; the result of the small differential index and large differential gain is low antiguiding.