1. Chair in Hybrid Nanosystems, Nanoinstitute Munich, Ludwig-Maximilians-Universität Munich, Königinstraße 10, 80539 Munich, Germany
2. Leibniz Institute of Photonic Technology, Albert-Einstein-Str. 9, 07745 Jena, Germany
3. Abbe Center of Photonics and Faculty of Physics, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany
4. Departmento de Física, Universidade Federal de Pernambuco, 50670-901 Recife-PE Brazil
5. Otto Schott Institute of Materials Research (OSIM), Friedrich-Schiller-Universität Jena, Fraunhoferstr. 6, 07743 Jena, Germany
6. School of Physics and Astronomy, Monash University, Clayton, Victoria 3800, Australia
7. The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2AZ, United Kingdom