1. Guangdong Provincial Key Laboratory of Optical Fiber Sensing and CommunicationsInstitute of Photonics TechnologyJinan University Guangzhou 510632 China
2. Department of PhysicsMaterials Science Program and National High Magnetic Field LaboratoryFlorida State University Tallahassee FL 32306 USA
3. State Key Laboratory of Luminescent Materials and DevicesSchool of Materials Science and EngineeringSouth China University of Technology Guangzhou 510641 China
4. Key Laboratory of Materials for High Power LaserShanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences Shanghai 201800 P. R. China
5. State Key Laboratory of Modern Optical InstrumentationCollege of Optical Science and EngineeringZhejiang University Hangzhou 310027 China