1. Institute of Photonics and Optical Science (IPOS), School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia
2. The University of Sydney Nano Institute (Sydney Nano), University of Sydney, Sydney, New South Wales 2006, Australia
3. Leibniz Institute of Photonic Technology (IPHT Jena), Albert-Einstein-Str. 9, 07745 Jena, Germany
4. Abbe School of Photonics and Faculty of Physics, Max-Wien-Platz 1, 07743 Jena, Germany
5. Otto Schott Institute of Materials Research, Fraunhoferstr. 6, 07743 Jena, Germany