Beijing University of Posts and Telecommunications, Beijing University of Posts and Telecommunications, affiliation not provided to SSRN, Beijing University of Posts and Telecommunications, South China Normal University - Guangzhou Key laboratory for Special Fiber Photonic Devices and Applications, South China Normal University, Beijing University of Posts and Telecommunications (BUPT), Beijing University of Posts and Telecommunications, Beijing University of Posts and Telecommunications (BUPT) and Beijing University of Posts and Telecommunications