1. State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, China
2. College of Biological and Agricultural Engineering, Jilin University, 5988 Renmin Street, Changchun 130022, China
3. College of Engineering, Shantou University, 243 Daxue Road, Shantou, 515063, P.R. China
4. Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA