1. Université Clermont Auvergne, CNRS, Clermont Auvergne INP, Institut Pascal, F-63000 Clermont-Ferrand, France
2. Faculty of Physics, St. Petersburg State University, Universitetskaya Embankment 13B, 199034 St. Petersburg, Russia
3. Department of Engineering Physics, McMaster University, Hamilton L8S4L7, Ontario, Canada