1Department of Optoelectrics Information Science and Engineering, School of Physics and Electronics, Central South University, Changsha 410012, China
2State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
3School of Electrical Engineering and Computer Science, Louisiana State University, Baton Rouge, Louisiana 70803, USA
4Center for Computation and Technology, Louisiana State University, Baton Rouge, Louisiana 70803, USA