1 Department of Physics, School of Science, Tianjin University, Tianjin, 300072, China.
2 Tianjin Key Laboratory of Molecular Optoelectronic Science, Institute of Molecular Plus, Tianjin University, Tianjin, 300072, China.
3 Department of Physics and Center for Optoelectronics and Photonics Paderborn (CeOPP), Universität Paderborn, Warburger Strasse 100, 33098, Paderborn, Germany. xuekai.ma@gmail.com.
4 Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, School of Science, Tianjin University, Tianjin, 300072, China.
5 Department of Physics and Center for Optoelectronics and Photonics Paderborn (CeOPP), Universität Paderborn, Warburger Strasse 100, 33098, Paderborn, Germany.
6 Wyant College of Optical Sciences, University of Arizona, Tucson, AZ, 85721, USA.
7 Department of Physics, School of Science, Tianjin University, Tianjin, 300072, China. tinggegao@tju.edu.cn.
8 Tianjin Key Laboratory of Molecular Optoelectronic Science, Institute of Molecular Plus, Tianjin University, Tianjin, 300072, China. tinggegao@tju.edu.cn.