1. Institute of Physical Science and Information Technology and the School of Electrical Engineering and Automation, Anhui University, Hefei, China
2. Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
3. School of Integrated Circuits, Peking University, Beijing, China