1. Department of Physics, Universitat Politècnica de Catalunya, Rambla Sant Nebridi 22, 08222 Terrassa, Spain
2. Charles M. Bowden Research Center, CCDC AVMC, Redstone Arsenal, Alabama 35898-5000, USA
3. ICFO – The Institute of Photonics Sciences, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain
4. AEgis Technologies, Inc., 401 Jan Davis Dr., Huntsville, Alabama 35806, USA