1. Electromagnetism and Telecom Department, University of Mons, 7000 Mons, Belgium
2. Foundation for Research and Technology Hellas (FORTH), Institute of Electronic Structure and Laser (IESL), 70013 Heraklion, Greece
3. School of Sciences, European University Cyprus/EUC Research Centre, 1516 Nicosia, Cyprus
4. Photonics Research Center (PRC), Lumoscribe Ltd., 8201 Paphos, Cyprus
5. Institute of Photonics and Electronics (UFE), The Czech Academy of Sciences, Chaberska 57, 8-Kobylisi, 18200 Prague, Czech Republic