1. Division
of Physics and Applied Physics, School of Physical and Mathematical
Sciences, Nanyang Technological University, 50 Nanyang Ave, Singapore 637371
2. CINTRA CNRS-NTU-Thales, UMI 3288, Singapore 637553
3. Tang Optoelectronics Equipment Co., Huatuo Road, Shanghai Zhangjiang Hi-Tech Park, No.
168, 3 B District, Shanghai 201203 China
4. Centre
for Disruptive Photonic Technologies, Nanyang Technological University, Singapore 637371
5. School
of Material Science and Engineering, Nanyang Technological University, Singapore 639798
6. Laboratory
for Nanotechnology, Instrumentation and Optics, University of Technology of Troyes, 10000 Troyes, France