[1] South China Normal Univ, Prov Key Lab Nanophoton Funct Mat & Devices, Guangzhou 510631, Peoples R China
[2] South China Normal Univ, Sch Informat & Optoelect Sci & Engn, Guangzhou 510006, Peoples R China
[3] South China Normal Univ, Sch Phys, Guangzhou 510006, Peoples R China