1. Department of Applied Physics, Donghua University, 2999 Renmin Rd. North, Songjiang District, Shanghai 201620, P. R. China
2. Guangxi Key Laboratory of Manufacturing System and Advanced Manufacturing Technology, School of Mechanical Engineering, Guangxi University, Nanning 530004, P. R. China
3. The Key Laboratory for Ultrafine Materials of The Ministry of Education, East China University of Science and Technology, Shanghai 200237, P. R. China
4. Instrumental Analysis and Research Center, Shanghai University, Shanghai 200444, P. R. China
5. School of Materials Science and Engineering, Donghua University, P. R. China
6. Institute of Nonlinear Science, Donghua University, P. R. China