1. Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Macao SAR, P. R. China
2. School of Electronic and Information Engineering, Foshan University, Foshan 528000, P. R. China
3. State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, P. R. China
4. Department of Physics and Chemistry, Faculty of Science and Technology, University of Macau, Macao SAR, P. R. China