2 Institute of Physics and Technology, Russian Academy of Sciences, Moscow 117218, Russia
3 Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan
4 Center for Photonics and Infrared Engineering, Bauman Moscow State Technical University, Moscow 105005, Russia
5 Institute of Ultra High Frequency Semiconductor Electronics, Russian Academy of Sciences, Moscow 111005, Russia
6 Center for Integrated Electronics and Department of Electrical, Computer and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
Received 11 June 2014, accepted for publication 28 October 2014. Published 25 November 2014.
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