1 Institute of Electromagnetics and Acoustics and Key Laboratory of Electromagnetic Wave Science and Detection Technology, Xiamen University, Xiamen 361005, China
2 State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
3 Terahertz Research Center, University of Electronic Science and Technology of China, Chengdu 610054, China
4 Microsystem and Terahertz Research Center, China Academy of Engineering Physics, Mianyang 621900, China
5 School of Physical Science and Technology and Institute of Theoretical and Applied Physics, Soochow University, Suzhou 215006, China