1. Institute of Physics and Institute of Micro- and Nanotechnologies MacroNano, Technische Universität Ilmenau, PF 100565, 98684 Ilmenau, Germany
2. Fraunhofer Institute for Applied Solid State Physics, Tullastraße 72, 79108 Freiburg, Germany
3. Kyma Technologies Inc., 8829 Midway West Road, Raleigh, North Carolina 27617, USA