1. College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
2. Collaborative Innovation Center for Optoelectronic Science and Technology and Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, and College of Electronic Science and Technology, Shenzhen University, Shenzhen 518060, People's Republic of China
3. College of Communication Engineering, Jilin University, Changchun 130012, China
4. Department of Electro-Optics and Photonics, University of Dayton, Dayton, Ohio 45469, USA