1. Institute of Chemical Materials China Academy of Engineering Physics Mianyang 621900 P. R. China
2. University of Chinese Academy of Sciences Beijing 100190 P. R. China
3. School of Optoelectronics Science and Engineering University of Electronic Science and Technology of China Chengdu 611731 P. R. China
4. Center for Crystal Research and Development Key Laboratory of Functional Crystals and Laser Technology Department Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing 100190 P. R. China
5. Physikalisches Institut Universiät Stuttgart 70569 Stuttgart Germany