1. Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Science, East China Normal University, Shanghai 200241, People's Republic of China
2. National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Science, Shanghai 200083, People's Republic of China
3. Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, People's Republic of China