1. Department of Physics, School of Physics and Materials Science, Nanchang University 1 , Nanchang 330031, China
2. Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University 2 , Tianjin 300072, China
3. Institute of Space Science and Technology, Nanchang University 3 , Nanchang 330031, China
4. School of Medical Information and Engineering, Southwest Medical University 4 , Luzhou 646000, China