1. Faculty of Physics and Optoelectronic
Engineering, Guangdong University of Technology, Guangzhou 510006, People's Republic of China
2. Department of Biology
and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong S.A.R., People's Republic of
China
3. Department
of Physics, Anhui Normal University, Wuhu, Anhui
241000, People's Republic of China