针对克尔非线性效应限制系统性能的问题, 文章提出概率整形(PS)与相位共轭孪生波(PCTW)相结合的非线性抑制方案, 以提高光通信系统的性能。利用Optisystem和Matlab软件, 在十六进制、六十四进制正交幅度调制(QAM)两种调制格式下, 搭建由两种编码PS(哈夫曼编码和标志取反编码)和3种维度PCTW(时域、偏振域和子载波域)组合的PCTW-PS系统。仿真结果表明, PCTW和PS结合的方案最小误码率(BER)大幅度减小; 16QAM-时域PCTW方案BER较小。得到以下结论: PS和PCTW都可改善系统性能, 两者相结合可大幅扩大改善程度; 16QAM-时域PCTW方案性能较优。仿真结果同时表明, PCTW系统中, 同相分量I和正交分量Q 的BER存在一定差异, 据此, 文章提出PCTW-IQ不均衡的概念, 这种不均衡性在偏振域PCTW方案中尤其明显。

The Kerr nonlinear effect limits the performance of the system. A nonlinear suppression scheme combining Probability Shaping (PS) and Phase Conjugate Twin Wave (PCTW) is proposed to improve the performance of large capacity optical fiber communication system. With co-simulation of Optisystem software and Matlab software, a PCTW-PS system is built in 16 Quadrature Amplitude Modulation (16QAM) and 64QAM modulation formats. The system consists of two kinds of PS (Huffman coding, sign inversion coding) and three dimensions PCTW (time domain, polarization domain, sub-carrier domain) to form different combinations. The simulation results show that the minimum Bit Error Rate (BER) of the scheme combining PCTW and PS can be greatly reduced. The BER of 16QAM time domain PCTW scheme is smaller than other schemes. Therefore, it can be seen that both PS and PCTW can improve system performance. The combination of PS and PCTW can further improve the performance. The 16QAM-PCTW scheme in time domain has better performance than other schemes. The simulation results also show that the BER of the in-phase component I and the quadrature component Q is different in PCTW system. Therefore, the concept of PCTW-IQ imbalance is proposed and the imbalance is especially obvious for polarization domain PCTW scheme.