1. Institute of Nanotechnology Karlsruhe Institute of Technology Hermann‐von‐Helmholtz‐Platz 1 76344 Eggenstein‐Leopoldshafen Germany
2. Institute of Materials Science Technische Universität Darmstadt Alarich‐Weiss‐Straße 2 64287 Darmstadt Germany
3. Department of Physics Freie Universität Berlin Arnimallee 14 14195 Berlin Germany
4. Institute of Microstructure Technology Karlsruhe Institute of Technology Hermann‐von‐Helmholtz‐Platz 1 76344 Eggenstein‐Leopoldshafen Germany
5. Light Technology Institute Karlsruhe Institute of Technology Engesserstraße 13 76131 Karlsruhe Germany