[1] Center for Terahertz Waves, College of Precision Instruments and Optoelectronics Engineering, Tianjin University, No. 92 Weijin Road, Tianjin,300072, China
[2] Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Hong Kong,999077, Hong Kong
[3] The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen,518057, China