[1] Shandong Univ, Sch Informat Sci & Engn, Qingdao 266237, Peoples R China
[2] Xiamen Univ, Dept Phys, Xiamen 361005, Peoples R China
[3] City Univ Hong Kong, Dept Elect Engn, Hong Kong, Peoples R China
[4] Shandong Univ, Key Lab Laser & Infrared Syst, Minist Educ, Qingdao 266237, Peoples R China