1. ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
2. Physics Department, Faculty of Science, Al-Azhar University, Nasr City, E-11884 Cairo, Egypt
3. Donostia International Physics Center, Paseo Manuel Lardizabal 4, 20018 Donostia, San Sebastián,Spain
4. Centro de Física de Materiales CSIC-UPV/EHU and Materials Physics Center, 20018 San Sebastián, Spain
5. Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511, United States
6. Faculty of Engineering, Bar Ilan University, Ramat Gan 5290002, Israel
7. Departamento de Física Aplicada I, Universidad del País Vasco, E-20018 San Sebastián, Spain
8. ICREA-Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08010 Barcelona, Spain