1. College of Physics and Electronic Engineering, Yancheng Teachers University Yancheng, Jiangsu 224051, P. R. China
2. Department of Physics, Guangxi Medical University, Nanning, Guangxi 530021, P. R. China
3. The Laboratory of Biomedical Photonics and Engineering, Guangxi Medical University, Nanning Guangxi 530021, P. R. China
4. Department of Physics, College of Physics and Electronic Engineering, Guangzhou University, Guangzhou 510006, P. R. China
5. ENSET de Rabat, Universite Mohamed V Souissi, B. P. 6207, Rabat-Institut, Rabat, Morocco