1. Centre for Terahertz Waves and College of Precision Instrument and Optoeletronics Engineering, Tianjin University, Tinajin 300072, China
2. Department of Mathematics and Physics, North China Electric Power University, Baoding 071003, China
3. Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences, Chongqing 400714, China
4. Guangxi Key Laboratory of Optoelectronic Information Processing, School of Optoelectronic Engineering, Guilin University of Electronic Technology, Guilin 541004, China