[Xu, Si-Qin; Luo, Jian-Hua; Tan, Xiao-Long; He, Meng-Dong; Ma, Jin-Hong; Chen, Li-Qun; Li, Jian-Bo; Kuang, Zhi-Wei] Cent South Univ Forestry & Technol, Inst Math & Phys, Changsha 410004, Hunan, Peoples R China.
[Liang, Shan] Hunan Normal Univ, Dept Phys, Changsha 410081, Hunan, Peoples R China.
[Xiao, Si] Cent South Univ, Sch Phys & Elect, Hunan Key Lab Super Microstruct & Ultrafast Proc, Changsha 410083, Peoples R China.
[Kim, Nam-Chol] Kim Il Sung Univ, Dept Phys, Pyongyang, North Korea.