1. i3N & Physics Department, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
2. Leibniz Institute of Photonic Technology, Albert-Einstein-Str. 9, 07745 Jena, Germany
3. Otto Schott Institute of Materials Research (OSIM), Friedrich Schiller University of Jena, Fraunhoferstr. 6, 07743 Jena, Germany
4. Abbe Center of Photonics and Faculty of Physics, Friedrich Schiller University of Jena, Max-Wien-Platz 1, Jena 07743, Germany