1. Institute of Quantum Optics, Leibniz University Hanover, Hannover, Germany
2. Aston Institute of Photonic Technologies, Aston University, Birmingham, U.K.
3. Le Verre Fluoré, Campus KerLann, Bruz, France
4. Department of Electrical and Computer Engineering, Stony Brook University, Stony Brook, USA
5. Nanoplus GmbH, Gerbrunn, Germany
6. Technische Physik, Physikalisches Institut and Wilhelm Conrad Röntgen-Research Center for Complex Material Systems, University of Würzburg, Würzburg, Germany