1. School of Electronic and Computer Engineering, Shenzhen Graduate School, Peking University, Shenzhen 518055, 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 518060, China
3. School of Electronics and Information Technology, Sun Yat-Sen University, Guangzhou, China