1. Photonics Research Group, Ghent University - imec, 9052 Ghent, Belgium
2. NB Photonics, Ghent University, 9052 Ghent, Belgium
3. Single Quantum B.V., 2628 CJ Delft, The Netherlands
4. Optics Research Group, Delft University of Technology, 2628 CJ Delft, The Netherlands
5. Physics and Chemistry of Nanostructures Group, Ghent University, 9000 Ghent, Belgium
6. Department of Applied Physics, KTH, Stockholm 106 91, Sweden