1. College of Physics, University-Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, Qingdao 266071, China
2. National Demonstration Center for Experiment Applied Physics Education (Qingdao University), Qingdao 266071, China
3. Shandong Provincial University Key Laboratory of Optoelectrical Material Physics and Devices, Qingdao 266071, China