[Lan, Yu] Hengyang Normal Univ, Coll Phys & Elect Engn, Hunan Prov Key Lab Intelligent Informat Proc & Ap, Hengyang 421002, Hunan, Peoples R China.
[Lan, Yu] Univ Texas Dallas, Dept Phys, Richardson, TX 75080 USA.
[Ma, Xixiao] State Intellectual Property Off, Patent Off, Beijing 100088, Peoples R China.
[Qin, Ling] Chengdu Normal Univ, Coll Phys & Engn, Chengdu 611130, Sichuan, Peoples R China.
[Feng, Shiping; Wang, Yongjun] Beijing Normal Univ, Dept Phys, Beijing 100875, Peoples R China.