1. Microsystems Laboratory,
Institute of Microengineering, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
2. Aix Marseille
Univ, CNRS, Centrale Marseille, Institut Fresnel, F-13013 Marseille, France
3. ICFO-Institut
de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain
4. Interdisciplinary Center for Electron Microscopy (CIME) Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
5. ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain