1. Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia
2. Department of Physics, Politecnico di Milano, Piazza Leonardo Da Vinci 32, 20133 Milano, Italy
3. Department of Information Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy
4. CNR-INO (National Institute of Optics), Via Branze 45, 25123 Brescia, Italy
5. CNR-IFN, LNESS Laboratory, Via Anzani 42, 22100 Como, Italy
6. Department of Electrical Engineering and Computer Science, University of California, Irvine, California 92697, United States