1. The China−Germany Research Center for Photonic Materials and Device, State Key Laboratory of Luminescent Materials and Devices, and Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641, P. R. China
2. School of Applied Physics and Materials, Wuyi University, Jiangmen, Guangdong 529020, P. R. China
3. GE Global Research, 1 Research Circle, Niskayuna, New York 12309, United States
4. College of Mathematics and Physics, Chongqing University of Posts and Telecommunications, Chongqing 400065, P. R. China
5. Institute of Physics, University of Tartu, W. Ostwald Strasse 1, Tartu 50411, Estonia
6. Institute of Physics, Jan Długosz University, Armii Krajowej 13/15, Czȩstochowa PL-42200, Poland