1. Siyuan Laboratory Guangdong Provincial Engineering Technology Research Center of Vacuum Coating Technologies and New Energy Materials Department of Physics Jinan University Guangzhou Guangdong 510632 P.R. China
2. Guangzhou Research Institute of Optical Mechanical and Electronical Technologies Co., Ltd Guangzhou Guangdong 510663 P.R. China
3. Department of Physics Chemistry and Biology (IFM) Linköping University Linköping 58183 Sweden
4. Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications Jinan University Guangzhou Guangdong 510632 P.R. China
5. School of Electronic Science and Technology Nanjing University Nanjing Jiangsu 210093 P. R. China