1. Centre for Terahertz Waves and College of Precision Instrument and Optoeletronics Engineering, Tianjin University, Tinajin 300072, People's Republic of China
2. Tianjin Engineering Technology Center of Chemical Wastewater Source Reduction and Recycling, School of Science, Tianjin Chengjian University, Tianjin 300072, People's Republic of China
3. Tianjin Key Laboratory of Molecular Optoelectronic Science, Department of Chemistry, School of Sciences, Tianjin University, Tianjin 300354, China
4. School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, Oklahoma 74078, USA