1. School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore
2. CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Singapore 637553, Singapore
3. Key Laboratory of Optoelectronics Devices and Systems of Ministry of Education/Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, P. R. China
4. Institut d’Electronique, de Microélectronique et de Nanotechnologie (IEMN), CNRS UMR 8520—Université de Lille, 59650 Villeneuve d’Ascq, France
5. Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland 20892, United States