Synergistic equalization of frequency offset and polarization crosstalk in DP-CS-NFDM systems
LI Xusheng
XU Hengying
XU Yayun
ZHANG Yining
YANG Lishan
LI Xiaozheng
ZHUANG Conghao
Abstract：To address the issues of laser frequency offset and polarization crosstalk in dual-polarization con-tinuous-spectrum nonlinear frequency division multiplexing(DP-CS-NFDM)systems,we propose a syner-gistic equalization scheme of laser frequency offset and polarization crosstalk(SE-FO-PC).Based on the same short training sequence,this scheme simultaneously performs adaptive filter coefficient pre-updating and two-stage frequency offset estimation in the frequency and time domains,while incorporating a deci-sion-aided mechanism to optimize the filter coefficients,thereby effectively equalizing polarization crosstalk.Simulation results of 40 GHz DP-CS-NFDM system demonstrate that,with a laser linewidth of 100 kHz and a transmission distance of 1 440 km,the frequency offset estimation error of SE-FO-PC scheme remains below 1 MHz,demonstrating the broader applicability and higher estimation accuracy than the existing schemes.Furthermore,under a differential group delay of 180 ps,the proposed scheme requires only 3 burst training sequences to achieve polarization crosstalk equalization performance compara-ble to that of conventional schemes using 13 sequences,effectively enhancing the spectral efficiency of DP-CS-NFDM system.
Keywords：continuous spectrumnonlinear frequency division multiplexing systemsfrequency offset estimationpolarization crosstalk equalization
Publication Date：2026-06-25
Online Publishing Date：2026-08-28(First online date of this platform, not the publication date of the document)
Pages：8( 366-373 )