1. Center for Nanoscale Characterization & DevicesWuhan National Laboratory for OptoelectronicsHuazhong University of Science and Technology 1037 Luoyu Road Wuhan Hubei 430074 China
2. Engineering Research Center for Functional CeramicsMinistry of Education, School of Optical and Electronic InformationHuazhong University of Science and Technology 1037 Luoyu Road Wuhan Hubei 430074 China
3. School of PhysicsHuazhong University of Science and Technology 1037 Luoyu Road Wuhan Hubei 430074 China