Maes, Bjorn, <p class="Affiliation">Micro- and Nanophotonic Materials Group, Faculty of Science, University of Mons, Place du Parc 20, B-7000 Mons, Belgium</p> <p class="Affiliation">Photonics Research Group (INTEC), Ghent University-imec, Sint-Pietersnieuwstraat 41,<