Room temperature photoreflectance (PR) has been performed on InGaAs/AlAsSb quantum wells (QWs) grown on InP substrates. Using a differential reflectance setup, we observed clear and well-resolved structures, which could be attributed to the interband optical transitions originating in both the QWs and InP substrate. The transition energies measured from the PR spectra agree with those theoretically calculated from the confined levels in the QWs. (c) 2006 Elsevier B.V. All rights reserved.