1. Physics Department, University of Miami, Coral Gables, FL 33126, USA.
2. College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006, China.
3. Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
4. Physics Department, George Washington University, Washington D.C., 20052, USA.