基于背向瑞利散射的少模光纤模式耦合测量

Measurement of Mode Coupling in Few-Mode Fiber Based on Rayleigh Backscattering

少模光纤的模式耦合引起模分复用(MDM)系统传输性能劣化,是造成MDM技术难以在实际中大规模应用的主要因素之一。精确测量少模光纤模式耦合系数和量化分析模式耦合与系统性能之间的关系,可以为系统的损伤补偿提供可靠依据。分析了当前少模光纤模式耦合测量方法的利弊,并基于背向瑞利散射原理建立了一种模式转换器/解复用器和光纤环形器结构的少模光纤模式耦合测量系统,通过与多输入多输出功率分析的测量结果进行对比,验证了所提系统的测量性能。实验结果表明,所提系统较好地实现了对9.8km少模光纤模式耦合分布的测量,且测量结果稳定。

Mode coupling in few-mode fiber may cause the transmission performance deterioration of a mode division multiplexing （MDM） system, which is one of the major factors limiting MDM technology to be applied in practice on a large scale. Precise measurement of mode coupling coefficient in few-mode fiber and quantitative analysis on the relationship between mode coupling and the performance of MDM system can provide reliable basis for the system- damage compensation. The advantages and disadvantages of the present measuring methods for mode coupling in few mode fiber are analyzed, and a measurement system of mode coupling in few-mode fiber with the structure of mode transverter/demuhiplexer and an optical fiber circulator based on the Rayleigh backscattering theory is built. By compared with the measurement results of multiple-input-multiple-output power analysis, the measurement performance of the proposed system has been verified. The experimental results show that the proposed system can realize the measurement of the mode coupling distribution in few-mode fiber with the fiber length of 9.8 km, and the measurement results are stable.