1. Materials Research and Technology (MRT) Department, Luxembourg Institute of Technology, 41, Rue du Brill, Belvaux L-4422, Luxembourg
2. Laboratory Light, Nanomaterials & Nanotechnologies − L2n, University of Technology of Troyes and CNRS ERL 7004, 12 rue Marie Curie, 10000 Troyes, France
3. Optical Sciences Centre, Swinburne University of Technology, Hawthorn, VIC 3122, Australia