1. Institute of Solid State Physics, Technische Universität Berlin, 10623 Berlin, Germany
2. Department of Experimental Physics, Wroclaw University of Science and Technology, 50-370 Wrocław, Poland
3. Department of Optics and Photonics, Wroclaw University of Science and Technology, 50-370 Wrocław, Poland
4. Institute of Chemical Sciences, Maria Curie Sklodowska University, 20-031 Lublin, Poland
5. Fibrain Sp. z o.o., 36-062 Zaczernie, Poland
6. Zuse Institute Berlin, 14195 Berlin, Germany