1. School of Physics and Electronics, Academy for Advanced Interdisciplinary Studies, International Joint Research Laboratory of New Energy Materials and Devices of Henan Province, Henan University, Kaifeng 475004, P. R. China
2. Henan Key Laboratory of Infrared Spectrum Measures and Applications, Institute of Electromagnetic Wave, School of Physics, Henan Normal University, Xinxiang 453007, P. R. China