1. Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China, http://fclt.ipc.cas.cn/
2. Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
3. University of the Chinese Academy of Sciences, Beijing 100049, P. R. China