1. Department of Materials Science and Engineering Centre for Functional Photonics (CFP) City University of Hong Kong Hong Kong SAR 999077 P. R. China
2. State Key Laboratory of Superhard Materials Key Laboratory of Automobile Materials of MOE College of Materials Science and Engineering Jilin University Changchun 130012 P. R. China
3. Institute for Advanced Materials and Technology University of Science and Technology Beijing Beijing 100083 P. R. China