1. Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
2. Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW), 70563 Stuttgart, Germany
3. Light Technology Institute, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany