1. College of Physics and Electronic Information Science, Tianjin Normal University, Tianjin 300387, China
2. Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon, Hong Kong, China
3. Institute of Information Optics, Zhejiang Normal University, Jinhua, Zhejiang 321004, China
4. Department of Physics and Engineering Physics, The University of Tulsa, Tulsa, Oklahoma 74104, USA