• 42.55.Px;
  • 42.60.Lh;
  • 78.66.Fd


We present the investigation of an optimized epitaxial layer structure in order to reach high optical output powers of several watts. The influence of an interlayer, which is located between the multiple quantum well layers and the electron blocking layer, is analysed carefully. For high current densities the leakage current density increases with increasing interlayer thickness. Correlating the leakage current density with the injection efficiency it is found that by decreasing the interlayer thickness constant injection efficiency for high current regions can be reached. This is essential for a linear laser characteristic up to high optical output power levels. Further enhancement can be achieved by enlarging the total waveguiding layer structure. As a result the optical power density in the resonator was decreased. With these improvements threshold current density and slope efficiency of 2.7 kA/cm2 and 2.1 W/A can be achieved. The optical output power is increased to 8.7 W for a 20 μm broad single-emitter ridge-waveguide laser in pulsed operation. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)