1. Light Technology Institute (LTI), Karlsruhe Institute of Technology (KIT), Engesserstraße 13, D-76131 Karlsruhe, Germany
2. Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany