OAM模式复用光纤传输系统中串扰机制与补偿方法研究

Due to the continuous increase of video streaming and related new services, data trafficking in the optical fiber transmission system is rising exponentially. Recently, the new multiplexing technology, such as orbital angular momentum (OAM), has attracted significant attention. OAM can strongly enhance transmission capacity in the optical fiber system. However, several issues have arisen, which need to be addressed urgently. One of the biggest problems is the mode crosstalk of different OAM modes, which may increase the signal error rates and eventually jeopardize the performance of the optical fiber transmission system. The current project focuses on dissecting the basic mechanism of OAM mode crosstalk and seeking the innovative compensating approaches. We will first establish a matrix model of optical fiber transmission, closely related to the OAM mode crosstalk. Further, we will determine the crosstalk parameters based on Zernike polynomials, and elucidate the mechanism of OAM mode crosstalk. Finally, we will propose the compensation strategy for OAM mode crosstalk and verify it by detailed experimental approaches. With the combination of theoretical analysis and experimental verification, we will delineate the mechanism of OAM mode crosstalk and identify potential compensating means, with an aim to pave a way for the possible application of OAM multiplexing technology in the next generation of optical fiber transmission system.

随着视频流媒体等新业务的不断涌现，光纤传输主干网承载的数据流量急剧上升。轨道角动量（OAM）复用等增大传输容量的新型复用技术越来越得到研究者们的青睐。OAM复用技术在提高系统容量的同时，也带来了一系列亟待解决的问题，尤其是OAM模式间的串扰。OAM模式间的串扰会造成信号误码率增大，导致光纤通信系统的性能严重下降。本课题将围绕下一代光纤传输系统中新型复用技术的关键问题“OAM模式复用光纤传输系统中的串扰机制与补偿方法”基础理论及应用展开创新性研究。拟建立与OAM模式串扰相关的光纤传输系统的数学模型，给出利用泽尼克多项式确定串扰参数的方法，完成模式间串扰机制的研究；提出实现OAM模式串扰补偿的方案并进行实验验证。基于以上内容，通过理论分析和实验验证相结合的方式，健全一套基于OAM复用技术的新型模分复用光纤传输系统的串扰及补偿分析方法，为OAM复用技术在下一代光纤传输系系统中的应用奠定重要基础。

轨道角动量（OAM）复用等新型复用技术可在有限的波长带宽范围内提高系统的传输容量，有望用来解决日益增长的数据流量与光纤传输主干网承载容量之间的矛盾。OAM模式间的串扰会造成信号误码率增大，导致系统性能下降，是OAM复用光纤传输系统实用化需要解决的关键问题之一。本课题围绕下一代基于新型复用技术的光纤传输系统中OAM模式间的串扰机制和补偿方法进行了研究，研究内容及取得成果包括如下方面：设计了能够传输OAM模式的光子晶体光纤和折射率均匀分布的环状光纤等新型光纤，并分析了光纤中OAM模式的损耗、色散、非线性等传输性能；研究了环状光纤在受到微扰的条件下，理想本征模式之间发生耦合的机制，即信号发生串扰的根本原因；建立了微扰条件下光纤模式耦合理论，并给出了计算理想本征模式耦合系数的数值计算方法；提出了将泽尼克（Zernike）多项式法与随机并行梯度下降算法相结合，应用于OAM复用光纤传输系统补偿模式串扰的方案。此外，在本项目支持下还拓展完成了部分相关内容的研究：实现了OAM模式的产生和接收实验，设计了一种OAM模式掺铒光纤放大器和模式耦合器，研究了环状光纤中OAM模式偏振模色散的统计特性，拓展了光纤中模式串扰机制的研究。课题的研究成果为OAM复用技术在下一代光纤传输系统中的应用奠定重要基础。