We report on a high resolution X-ray diffraction analysis of three antimonide-based mid-infrared laser samples (designed for optical pumping) with an active type-II structure. The deformation of the layer unit cells is determined with high accuracy, taking into account relaxation, layer tilting, and asymmetrical strain. Layer compositions are determined and layer sequences are examined accurately also considering the results of reflective high-energy electron diffraction studies during growth. Layer thicknesses and strain values of the type-II structure quantum wells as well as stoichiometry of the mixed anion interfaces are extracted. By designing the antimonide-to -arsenide interfaces in sample II, we achieved exact lattice matching of the active region to the substrate. Based on the knowledge of the determined structural parameters, non-radiative recombination processes are investigated with time resolved photoluminescence as well as laser properties under optically pumped laser operation. (C) 2003 Elsevier B.V. All rights reserved.