1. Department of Applied Physics, KTH Royal Institute of Technology, S-10691 Stockholm, Sweden
2. College of Chemistry and Molecular Sciences, Henan University, Kaifeng, Henan 475004, P. R. China
3. Henan Center for Outstanding Overseas Scientists, Henan University, Kaifeng 475004, P. R. China
4. Centre for Optical and Electromagnetic Research, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P.R. China
5. MOE Key Laboratory of Laser Life Science, Guangdong Engineering Research Centre of Optoelectronic Intelligent Information Perception, South China Normal University, Guangzhou 510631, P.R. China
6. Key Laboratory of New Energy and Rare Earth Resource Utilization of State Ethnic Affairs Commission, Key Laboratory of Photosensitive Materials & Devices of Liaoning Province, School of Physics and Materials Engineering, Dalian Minzu University, 18 Liaohe West Road, Dalian 11660, P.R. China