1. Key Laboratory of All Optical Network and Advanced Telecommunication Network of EMC Institute of Lightwave Technology Beijing Jiaotong University Beijing 100044 China
2. School of Electrical Engineering and Telecommunications UNSW Sydney Sydney New South Wales 2052 Australia
3. Functional Materials and Microsystems Research Group and the Micro Nano Research Facility RMIT University Melbourne Victoria 3000 Australia
4. School of Electrical and Electronic Engineering The University of Adelaide Adelaide South Australia 5005 Australia
5. School of Physics and Institute of Photonics and Optical Science (IPOS) The University of Sydney Camperdown New South Wales 2006 Australia