1. College of Physics, Qingdao University, Ningxia Road No. 308, Qingdao 266071, China
2. College of Physics, University-Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, Qingdao 266071, China
3. Qingdao Broadband Terahertz Spectroscopy Technology Engineering Research Center, Qingdao University, Qingdao 266071, China