[1] Yantai Univ, Dept Phys, Yantai 264005, Peoples R China
[2] Hebei Univ, Coll Phys Sci & Technol, Baoding 071002, Peoples R China
[3] Shandong Univ, Sch Informat Sci & Engn, Qingdao 266237, Peoples R China
[4] Beijing Normal Univ, Dept Phys, Appl Opt Beijing Area Major Lab, Beijing 100875, Peoples R China