1. State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques School of Materials Science and Engineering South China University of Technology Guangzhou 510641 China
2. Department of Chemistry City University of Hong Kong Kowloon Hong Kong 999077 China
3. Laboratory of Crystal Physics Kirensky Institute of Physics Federal Research Center KSC SB RAS Krasnoyarsk 660036 Russia
4. Department of Engineering Physics and Radioelectronic Siberian Federal University Krasnoyarsk 660041 Russia
5. Research and Development Department Kemerovo State University Kemerovo 650000 Russia
6. Department of Physics University of the Free State P.O. Box 339 Bloemfontein ZA‐9300 South Africa
7. School of Physics and Optoelectronics South China University of Technology Guangzhou 510641 P. R. China