1. State Key Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai 200083, China
2. Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
3. University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
4. School of Physics and Electronics, Hunan Key Laboratory for Supermicrostructure and Ultrafast Process, Central South University, 932 South Lushan Road, Changsha, Hunan 410083, China