[1] National Key Laboratory of Photoelectric Technology and Functional Materials, Northwest University, Xi'an 710069, China
[2] Natl. Photoelectric Technol. and Funct. Mat. and Appl. of Science and Technol. Intl. Coop. Center, Northwest University, Xi'an 710069, China
[3] Institute of Photonics and Photon-Technology, Northwest University, Xi'an 710069, China
[4] Department of Physics, Northwest University, Xi'an 710069, China