1. Key Laboratory of In-Fiber-Integrated Optics, Ministry of Education, College of Science, Harbin Engineering University, Harbin150001, China
2. Harbin Medical University Cancer Hospital, Harbin Medical University, Harbin150001, China
3. Photonics Research Center, Guilin University of Electronics Technology, Guilin541004, China
4. Wireless and Optoelectronics Research and Innovation Centre, Faculty of Computing, Engineering and Science, University of South Wales, Pontypridd CF37 1DL, U.K.