1. Laboratory of Photonic Materials and Fibre Devices (FIMAP); Institute of Materials; Ecole Polytechnique Fédérale de Lausanne (EPFL); Lausanne 1015 Switzerland
2. Group of Electrical Engineering of Paris (GeePs); 91192 Gif sur Yvette Cedex France
3. Sorbonne Iniversités; UPMC Univ Paris 06 UMR 8507 Paris France
4. Laboratory of Computational Science and Modeling (COSMO); Institute of Materials; Ecole Polytechnique Fédérale de Lausanne (EPFL); Lausanne 1015 Switzerland