1. Laboratory of Infrared Materials and Devices, The Research Institute of Advanced Technologies, Ningbo University, Fenghua Road 818#, Jiangbei District, Ningbo 315211, PR China
2. Key Laboratory of Photoelectric Detection Materials and Devices of Zhejiang Province, Ningbo University, Fenghua Road 818#, Jiangbei District, Ningbo 315211, PR China
3. Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, PR China