1. Photonics Institute, Technische Universität Wien, 1040 Vienna, Austria
2. Wigner Research Centre for Physics, Institute for Solid State Physics and Optics, 1121 Budapest, Hungary
3. Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
4. Fraunhofer Institute for Applied Optics and Precision Engineering, 07745 Jena, Germany
5. Institute for Optics and Quantum Electronics, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany
6. SwissFEL, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland