1. Otto Schott Institute of Materials Research
2. Friedrich Schiller University Jena
3. Fraunhoferstraße 6
4. 07743 Jena
5. Germany
6. State Key Laboratory of Luminescent Materials and Devices
7. Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques
8. and Institute of Optical Communication Materials
9. South China University of Technology
10. Guangzhou 510641