1. Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan
2. Institute of Ultra High Frequency Semiconductor Electronics of RAS, Moscow 117105, Russia
3. Center of Photonics and Two-Dimensional Materials, Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russia
4. Center for Photonics and Infrared Engineering, Bauman Moscow State Technical University, Moscow 111005, Russia
5. Department of Computer Science and Engineering, University of Aizu, Aizu-Wakamatsu 965-8580, Japan
6. Department of Electrical Engineering, University at Buffalo, Buffalo, New York 1460-192, USA
7. Department of Electrical, Computer, and Systems Engineering and Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
8. Electronics of the Future, Inc., Vienna, Virginia 22181, USA