面向模分复用的矩形纤芯光纤及其非线性补偿研究

For existing mode-division multiplexing (MDM) systems, insufficient numbers of modal channels and inadequate suppressions of modal crosstalk have posed great challenges to the increase of modal multiplicity factor and to the decrease of signal processing complexity. Rectangular-core fibers (RCFs) possess advantages of polarization degeneracy, favorable modal profiles for device coupling, and modal area uniformity, and thus, have become a new candidate for few-mode transmission fibers. In addition, few-mode phase-conjugated twin wave (PCTW) transmission can cancel out signal-to-signal nonlinear interactions, and has been considered as a means to improve the signal-to-noise ratio in MDM systems. This project plans to study the waveguide characteristics of RCFs and the PCTW technique for compensating nonlinear impairments in RCF-MDM transmissions, aiming to decrease the modal impairments, increase the number of modal channels, and enhance the system performance and capacity for the RCF-MDM transmission scenario. Specifically, we focus our researches on the following three aspects. Firstly, we investigate the comprehensive design and optimize strategies of rectangular core transmission fibers. Secondly, we analyze the random modal impairments in RCF transmissions and their mathematical-physical model. Thirdly, through combining RCF-MDM transmission and few-mode PCTW configuration, we explore the compensation effectiveness of few-mode PCTW for nonlinear effects. The anticipated results of this project will contribute to the establishment of the complete physical model of RCF-MDM transmissions, and lay theoretical and technological foundations for the engineering applications of RCF-MDM systems.

现有模分复用传输中存在模式信道数量不充足、模式串扰抑制不充分的问题，对提高模式复用倍增因数和降低信号处理复杂度带来极大挑战。矩形纤芯光纤具有偏振简并性、易与光器件耦合、众模式面积均一化等优点，是少模传输光纤的崭新选择；而少模相位共轭孪生波传输可消除信号间的非线性交互作用，是改进模分复用系统信噪比的有效途径。本项目面向矩形纤芯光纤中的模分复用传输场景，以减小模式损伤、增加模式信道数量、提升系统性能和容量为指引，研究矩形纤芯光纤的波导特征及其模分复用传输非线性损伤的相位共轭孪生波补偿方法。本项目拟具体在三个方面开展工作：（1）矩形纤芯传输光纤的全面设计及优化策略；（2）矩形纤芯光纤传输的随机模式损伤及其数理模型；（3）矩形纤芯光纤中的少模相位共轭孪生波传输及其对模分复用非线性效应的补偿效用。预期成果将推动矩形纤芯光纤中模分复用传输完整物理模型的建立，并为其工程应用奠定坚实的理论基础和技术储备。

为应对模分复用光传输系统中的模式信道数量不充足、模式串扰抑制不充分的问题，本项目研究了矩形纤芯光纤的优化设计和非线性补偿，旨在提高模式复用倍增因数和降低信号处理复杂度。本项目以矩形纤芯光纤中的模分复用传输为基本场景，充分研究了矩形纤芯光纤的波导特征及其模分复用传输非线性损伤的相位共轭孪生波补偿方法，从而寻求减小模式损伤、增加模式信道数量、提升系统性能和容量。在具体研究过程中，本项目在如下三个方面开展了具体的研究工作：（1）提供了矩形纤芯传输光纤的全面设计及优化策略；（2）对矩形纤芯光纤传输的随机模式损伤及其数理模型进行了深入梳理；（3）量化分析了矩形纤芯光纤中的少模相位共轭孪生波传输及其对模分复用非线性效应的补偿效用。本项目的研究结果有利于矩形纤芯光纤中模分复用传输完整物理模型的建立，可为其工程应用奠定坚实的理论基础和技术储备。