Carrier and Light Trapping in Graded Quantum Well Laser Structures
  We investigated the carrier and light trapping in GaInAs/AlGaAs single quantum well laser structures by means of time resolved photoluminescence and Raman spectroscopy. The influence of the shape and depth of the confinement potential and of the cavity geometry was studied by using different AlGaAs/GaAs short-period superlattices as barriers. Our results show that grading the optical cavity improves considerably both carrier and light trapping in the quantum well, and that the trapping efficiency is enhanced by increasing the graded confining potential. 
G. Aichmayr, M.D. Martin, H. van der Meulen, C. Pascual, L. Vina, J.M.   Calleja, F. Schafer, J. P. Reithmaier, and A. Forchel