1. School of Optoelectronic Engineering, Guangdong Polytechnic Normal University, Guangzhou 510665, China
2. Department of Physics, Shanghai Normal University, Shanghai 200234, China
3. Key Laboratory for Submillimeter Astrophysics, Shanghai Normal University, Shanghai 200234, China
4. School of Physics, Hefei University of Technology, Hefei 230009, China
5. Industrial Training Center, Guangdong Polytechnic Normal University, Guangzhou 510665, China