Affiliation: | a Beijing Key Lab for Terahertz Spectroscopy and Imaging, Capital Normal University, No.105 Xisanhuan Beilu, BeiJIng 100037, Chinab School of Engineering, Peking University, No. 8 YiHeYuan Rd, Beijing 100871, Chinac Department of Optical Engineering, Beijing Institute of Technology, No.5 Zhongguancun Nandajie, Beijing 100081, China |