1. Key
Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, People’s Republic of China
2. Center
for Terahertz Waves and College of Precision Instrument and Optoelectronics
Engineering, Tianjin University, Tianjin 300072, People’s Republic of China
3. Engineering
Research Center of Optical Instrument and System, Ministry of Education, University of Shanghai for Science and Technology, Shanghai 200093, People’s Republic of China