1. School of Electrical Engineering
2. Dalian University of Technology
3. Dalian
4. China
5. Key Laboratory of Materials Modification by Laser, Ion and Electron Beams
6. School of Physics and Materials Engineering
7. Dalian Minzu University
8. Dalian 116600
9. School of Physics and Electronic Technology
10. Liaoning Normal University
11. Dalian 116024