1. Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan
2. Center for Photonics and Infrared Engineering, Bauman Moscow State Technical University and Institute of Ultra High Frequency Semiconductor Electronics of RAS, Moscow 111005, Russia
3. Department of Computer Science and Engineering, University of Aizu, Aizu-Wakamatsu 965-8580, Japan
4. Department of Electrical Engineering, University at Buffalo, SUNY, Buffalo, New York 1460-1920, USA
5. Department of Electrical, Computer, and System Engineering and Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180, USA