1. Univ. Lille, CNRS, UMR 8523 - PhLAM - Physique des Lasers Atomes et Molécules, Lille, France
2. B. I. Stepanov Institute of Physics, NASB, Minsk, Belarus
3. Max Planck Institute for the Science of Light, Erlangen, Germany
4. School of Physics and Astronomy, University of St. Andrews, SUPA, St. Andrews, UK
5. Department of Physics, M. V. Lomonosov Moscow State University, Moscow, Russia