1. Wuhan
National Laboratory for Optoelectronics (WNLO) and School of Optical
and Electronic Information, Huazhong University of Science and Technology (HUST), Wuhan 430074, China
2. Key
Laboratory for Polar Materials and Devices (MOE), East China Normal University, Shanghai 200241, China, and Physics Department, Fudan University, Shanghai 200433, China
3. Institute
of Super-microstructure and Ultrafast Process in Advanced Materials,
School of Physics and Electronics, The Central South University, Changsha, Hunan 410083, China