1. Department of Physics and Namur Institute of Structured Materials, University of Namur, Rue de Bruxelles 61, 5000 Namur, Belgium
2. John A. Paulson School of Engineering and Applied Sciences, Harvard University, 9 Oxford Street, Cambridge, Massachusetts 02138, United States
3. Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, Virginia 23284, United States
4. Department of Electrical, Electronic and Communications Engineering, Institute of Smart Cities (ISC), Public University of Navarre (UPNA), Pamplona 31006, Spain
5. Faculty of Engineering and Natural Science, Photonics, Tampere University, 33720 Tampere, Finland
6. Departamento de Física Téorica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
7. Instituto de Telecomunicações, Instituto Superior Técnico-University of Lisbon, Avenida Rovisco Pais 1, Lisboa, 1049-001, Portugal
8. Photonics Initiative, Advanced Science Research Center, City University of New York, New York, New York 10027, United States
9. National Institute of Telecommunications (Inatel), Santa Rita do Sapucaí, 37540-000 MG, Brazil
10. Department of Physics, NLHT Lab, University of Calabria, 87036 Rende, Italy
11. CNR NANOTEC-Institute of Nanotechnology, Rende (CS), 87036 Rende, Italy
12. Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
13. Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
14. Department of Physics, Umeå University, Linnaeus väg 24, 90187 Umeå, Sweden
15. Department of Physics and Materials Science, University of Luxembourg, 162a avenue de la Faïencerie, L-1511 Luxembourg, Luxembourg