1. Laboratory of Photonics and Quantum Measurements (LPQM), Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
2. CONNECT Research Centre, Dunlop Oriel House, Trinity College Dublin, Dublin 2, Ireland.
3. Photonics Systems and Sensing Lab., School of Electronic Engineering, Dublin City University, Glasnevin D 9, Ireland.