1. Institute of Microscale Optoelectronics (IMO) Shenzhen University Shenzhen 518060 China
2. School of Physics and Telecommunication Engineering Yulin Normal University Yulin 537000 China
3. School of Physics and Electronics Hunan University Changsha 410082 China
4. College of Physics and Optoelectronic Engineering Key Lab of Optoelectronic Devices and Systems of Ministry of Education/Guangdong Province Shenzhen University Shenzhen 518060 China