An improved active region concept for highly efficient GaSb-based optically in-well pumped vertical-external-cavity surface-emitting lasers

An improved active region concept for GaSb-based optically pumped vertical-external-cavity surface-emitting lasers (VECSELs) is presented. The concept is based on Ga(x)In(1-x)As(y)Sb(1-y) quantum wells embedded between AlAs(y)Sb(1-y) barrier layers designed for optical in-well pumping. Advantages of this concept are a high modal gain, the suppression of thermal leakage currents, and an improved thermal conductivity of the active region compared to a conventional GaInAsSb/AlGaAsSb active region design. An in-well pumped VECSEL emitting at 2.24 µm has been realized according to this concept, yielding at a heatsink temperature of 20 °C in continuous-wave operation a power slope efficiency of more than 32% and an absorption of the 1.96 µm pump light of more than 50% without pump recycling.