1. State Key Laboratory of Precision Spectroscopy Engineering Research Center of Nanophotonics & Advanced Instrument Ministry of Education School of Physics and Electronic Science East China Normal University Shanghai 200241 P. R. China
2. School of Materials Science and Engineering Zhengzhou University 75 Daxue Road Zhengzhou 450052 P. R. China
3. Chinese Academy of Sciences State Key Lab of Transducer Technology Shanghai Institute of Microsystem and Information Technology Shanghai 200050 P. R. China