1. Department of Physics University of Calabria 87036 Arcavacata di Rende Cosenza Italy
2. CNR-Lab. Licryl Institute NANOTEC Arcavacata di Rende 87036 Italy
3. Department of Biosystems and Soft Matter Institute of Fundamental Technological Research Polish Academy of Sciences Warsaw 02-106 Poland
4. Beam Engineering for Advanced Measurements Company Orlando FL 32810 USA
5. Materials and Manufacturing Directorate Air Force Research Laboratory Wright-Patterson Air Force Base OH 45433-7707 USA
6. Department of Medico-Surgical Sciences and Biotechnologies Center for Biophotonics Sapienza University of Rome Corso della Repubblica 79 04100 Latina Italy