[Wang, Mingfeng; Chen, Jiaojiao; Li, Zhuanxia; Xiong, Wei] Wenzhou Univ, Dept Phys, Wenzhou 325035, Zhejiang, Peoples R China.
[Chen, Jiaojiao] Hefei Presch Educ Coll, Hefei 230013, Peoples R China.
[Luo, Xiao-Qing] Univ SouthChina, Sch Elect Engn, Hunan Prov KeyLab Ultrafast Micro Nano Technol &, Hengyang 421001, Peoples R China.
[Li, Hai-Chao] Hubei Normal Univ, Coll Phys & Elect Sci, Huangshi 435002, Hubei, Peoples R China.