相干光OFDM/OQAM系统相位噪声机理及抑制方法研究

交错正交幅度调制的相干光正交频分复用（相干光OFDM/OQAM）是构建下一代高光谱效率、弹性光网络的关键技术。但是，相干光OFDM/OQAM对光相位噪声的高敏感性极大地限制了其应用。已有的研究缺乏对其光相位噪声机理的完整分析，对光相位噪声扰动下的符号间串扰（ISI）和子载波间串扰（ICI）抑制效果不佳。本课题研究相干光OFDM/OQAM中光相位噪声机理及高效抑制方法。我们将解析分析光相位噪声对实数正交体系中固有的复数域ISI/ICI的扰动，首次完整阐明光相位噪声机理，并提出新颖的时域/频域高效光相位噪声抑制算法，以及光相位噪声/信道时域联合估计算法，分析原型滤波器的时频聚焦特性对光相位噪声容忍度的影响。我们将阐明算法原理，在采用低成本大线宽光源（不低于1MHz）高速（不低于400Gb/s）实验系统中验证算法可行性。本课题对推动高光谱效率相干光OFDM/OQAM在未来网络中应用具有重要价值。

Coherent optical orthogonal frequency division multiplexing with Offset Quadrature Amplitude Modulation (CO-OFDM/OQAM) is one key technology for the next-generation high spectrum efficiency and flexible optical networks. However, CO-OFDM/OQAM is very sensitive to optical phase noise, which hinders its application. In previous studies of CO-OFDM/OQAM, there is no comprehensive investigation of the mechanism of optical phase noise effect in the CO-OFDM/OQAM system, and the performance of inter-symbol-interference (ISI) suppression and inter-channel-interference (ICI) suppression in the CO-OFDM/OQAM system under the impact of optical phase noise is poor. In this project, we propose to conduct research on the mechanism of optical phase noise effect in the CO-OFDM/OQAM system and develop effective methods for optical phase noise suppression. We will derive the closed-form expression of the impact of optical phase noise on the ISI/ICI that exist in the real-orthogonality based CO-OFDM/OQAM system, and present a comprehensive expression of the mechanism of optical phase noise effect in CO-OFDM/OQAM system for the first time. We will develop novel and high-performance time/frequency domain optical phase noise suppression algorithms and high-accuracy time domain algorithms for joint estimation of optical phase noise/channel, and analyze the impact of the time/frequency localization characteristic of prototype filter on its tolerance to optical phase noise. We will present the principle of algorithms and conduct experimental investigation of their feasibility in a high speed (no less than 400Gb/s) CO-OFDM/OQAM communication system based on low-cost lasers of large linewidths (no less than 1MHz). This project is of great value for promoting the application of the high spectrum efficiency CO-OFDM/OQAM system in future optical networks.