1. Department of Electrical and Computer Engineering, University of Maryland and Institute for Research in Electronics and Applied Physics (IREAP), 8279 Paint Branch Dr., College Park, Maryland 20742, USA
2. Laboratoire Interdisciplinaire Carnot de Bourgogne, CNRS and Univ. Bourgogne-Franche-Comté, 9 Avenue A. Savary, 21078 Dijon, France
3. Key Lab of Micro-Nano Optoelectronic Information System, Ministry of Industry and Information Technology, School of Science, Harbin Institute of Technology, Shenzhen 518055, China
4. Instituto de Física Interdisciplinar y Sistemas Complejos, IFISC (CSIC-UIB), Campus Universitat de les Illes Balears, E-07122 Palma de Mallorca, Spain