1. University Grenoble Alpes, CEA-LETI, Minatec, Optics and Photonics Division, 17 rue des Martyrs, F-38054 Grenoble, France
2. DTU Fotonik, Technical University of Denmark, Kgs. DK-2800 Lyngby, Denmark
3. Institut des nanotechnologies de Lyon, UMR CNRS 5270, Ecole Centrale Lyon, F-69130 Ecully, France