1. Department of Electrical
Engineering and Computer Science, University of Siegen, Hölderlinstrasse
3, 57076 Siegen, Germany
2. WITec Wissenschaftliche Instrumente und Technologie GmbH, Lise-Meitner-Strasse
6, 89081 Ulm, Germany
3. Graphenea S.A., Avenida de Tolosa 76, 20018 San Sebastián, Spain
4. School of Information and Communication
Technology, KTH Royal Institute of Technology, E229, 16440 Kista, Sweden