基于科尔相位解调仪的光纤偏振模色散快速高精度测量技术研究

The characteristic of broad-band data transmission makes optical fiber communication stands out from the rest in the field of optical communication. Ultra-high-speed and long-distance data transmission requires further band-broadening for optical fiber communication. Measurement of polarization mode dispersion (PMD) of an optical fiber is significant to realize bandwidth broadening of the optical fiber communication system. The study of our newly developed Kerr phase-interrogator provides a new route for PMD measurement. On the basis of our prior work, this project studies the Kerr phase-interrogator and aims to: (1) Theoretically analyze the nonlinear interaction between orthogonally polarized sinusoidal optical signals using vector nonlinear Schrödinger equation, and study the working principle of PMD measurement based on the Kerr phase-interrogator; (2) Study the intensity noise of fiber Raman amplification, and optimize the optical amplification scheme to realize PMD measurement with high-resolution; (3) Design the measurement setup based on the Kerr phase-interrogator, and perform the fast PMD measurement with high resolution for a long optical fiber. This project will enhance our understanding of the Kerr phase-interrogator, and will provide a fast, simple, low-cost and accurate approach for PMD measurement. The implementation of this project will benefit the optical fiber communication system in terms of bandwidth and transmission distance.

光纤通信因通信频带宽，从光通信中脱颖而出，成为现代通信的主要支柱。超高速、长距离的信息传输对宽频带光纤通信有了更为迫切的需求。光纤偏振模色散是限制光纤通信带宽的主要因素，测量光纤偏振模色散是提高光纤通信带宽的前提。最近，我们提出的科尔相位解调仪为测量偏振模色散提供新思路。本课题在前期工作基础上，拟以科尔相位解调仪为研究对象，旨在：（1）利用矢量非线性薛定谔方程，研究偏振正交正弦光信号的非线性相互作用，建立科尔相位解调仪测量光纤偏振模色散的理论模型；（2）研究光纤拉曼放大技术的强度噪声特性，降低科尔相位解调仪中光放大强度噪声，为实现高精度测量提供理论支持；（3）设计基于科尔相位解调仪的偏振模色散测量系统,实现长距离通信光纤偏振模色散的快速、高精度测量。本课题的开展有助于深化对科尔相位解调仪的理解，为光纤偏振模色散测量提供快速、简单、高精度的方法，对拓展光纤通信带宽，增大通信距离具有重要意义。

本项目以科尔相位解调仪（Kerr phase-interrogator, KPI）为研究对象，建立了基于KPI的光纤偏振模色散（Polarization mode dispersion, PMD）测量理论模型，设计了用于KPI的低噪声光放大方案，提出了KPI系统误差抑制方法，搭建了一套基于KPI的光纤PMD测量系统，对光纤的双折射和双折射色散进行了测量，验证了光纤PMD测量能力。项目按照计划执行，具体执行情况如下所述：开展了基于KPI的光纤PMD测量理论模型研究。利用矢量形式的非线性薛定谔方程，阐明了偏振正交的两个正弦光信号在通信光纤中的相互作用，通过求解非线性薛定谔方程，得到了KPI输出光功率与偏振正交的两个光信号之间由PMD引起的时延的解析关系。开展了基于KPI的光纤PMD测量系统的优化研究。对比研究不同光放大方案的特点，根据各个光放大方案所能提供的信号增益，结合光信号在科尔介质中传播过程中偏振态的演变特性，设计了基于掺铒光纤放大器的低噪声光放大方案，降低PMD的测量噪声；采用保偏光纤主轴错位熔接方案，极大降低由构成KPI的保偏光纤引入的额外时延，降低了PMD测量系统的系统误差。开展了PMD测量的实验研究。设计并搭建基于KPI的光纤PMD测量系统，成功测量了通过保偏光纤两个主轴的正弦光信号的时延，获得了该保偏光纤的双折射和双折射色散信息，验证了测量系统测量光纤PMD的可行性。在本项目执行期间，项目负责人发表学术论文10篇，其中SCI检索4篇，EI检索6篇。