1. University of Normandie, UNIHAVRE, Laboratoire Ondes et Milieux Complexes, UMR CNRS 6294, 75 Rue Bellot, 76600 Le Havre, France
2. University of Tours, GREMAN, UMR CNRS 7347, 03 Rue de la Chocolaterie, 41000 Blois, France
3. Department of Physics, University of Torino, Via Pietro Giuria 1, 10125 Torino, Italy