远程干涉型光纤传感系统的非线性相位噪声分析

以远程干涉型光纤传感系统为背景, 研究了系统非线性相位噪声构成, 对各构成要素的具体影响进行了详细分析和综合评价, 简要讨论了噪声抑制方案. 研究表明, 系统相位噪声主要包括强度噪声转化而来的相位噪声、非线性效应引起激光 线宽展宽导致的相位噪声以及自相位调制和交叉相位调制引入的相位噪声. 受激布里渊散射和四波混频可引入强度噪声并转化为相位噪声, 对于探测带宽较窄的光纤传感系统, 四波混频引入的该部分噪声往往可以忽略. 受激布里渊散射、四波混频和调制不稳定性都可引起激光线宽展宽从而造成相位噪声的增大. 当系统信道数目较多时, 交叉相位调制对相位噪声的贡献不可忽略. 所得结论对远程干涉型光纤传感系统的实际应用具有重要的指导意义.

Nonlinear phase noise analysis of long-haul interferometric fiber sensing system

Nonlinear phase noise structure is studied in the background of long-haul interferometric fiber sensing system. The influence of each factor is analyzed and evaluated in detail, and suppression methods are discussed briefly. The results show that phase noise of the system mainly includes the phase noise converted from intensity noise, the phase noise caused by nonlinear effects induced laser linewidth variations as well as the phase noise introduced by self phase modulation and cross phase modulation. Stimulated Brillouin scattering and four-wave mixing can cause intensity noise and then it turns into phase noise. For the fiber sensing system which has a narrow detecting bandwidth, the corresponding noise induced by four-wave mixing can always be neglected. Stimulated Brillouin scattering, four-wave mixing and modulation instability can cause laser linewidth broadening, leading to the increase of phase noise. When the number of channels is large, the phase noise introduced by cross phase modulation cannot be ignored. The obtained results provide a good guidance for the practical applications of long-haul interferometric fiber sensing systems.