1. Institute of Optics and Quantum Electronics, Friedrich-Schiller University Jena, Max-Wien-Platz 1, 07743 Jena, Germany
2. Helmholtz-Institut Jena, Helmholtzweg 4, 07743 Jena, Germany
3. Abbe Center of Photonics, Albert-Einstein-Straße 6, 07745 Jena, Germany
4. Institute for Photonics, Vienna University of Technology, Gußhausstrasse 25-29, 1040 Vienna Austria
5. Institute of Solid State Physics, Friedrich-Schiller University Jena, Max-Wien-Platz 1, 07743 Jena, Germany