1. Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin 150001, China
2. College of Physics and Optoelectronic Engineering, Harbin Engineering University, Harbin 150001, China
3. State Key Laboratory of Molecular Engineering of Polymers, Key Laboratory of Computational Physical Sciences, Department of Macromolecular Science, Fudan University, Shanghai 200433, China