1. College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
2. College of Engineering and Applied Sciences, Nanjing University, Nanjing 211102, China
3. Laser Research Group, Physics Department and Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
4. Department of Physics, Southeast University, Nanjing 211189, China