The loop configuration consisting of a lead fiber and a sensing fiber is a common approach to realize Brillouin Optical Time-Domain Analysis (BOTDA), which is however impractical to implement for some field scenarios where only a single fiber is physically available. In this paper, a novel single-fiber-based BOTDA with far-end modulation is proposed and experimentally demonstrated, in which an auxiliary light and a pulse are injected from the near-end of the fiber, and the counter-propagating probe light is generated by modulating the auxiliary light from the far-end. By dedicatedly designing the frequency and temporal profile of each lightwave, Brillouin interaction takes place only between the pulse and the probe light, while stray effects such as four wave mixing and Rayleigh beating noise are avoided, which constitutes the key advantage of the propose technique with respect to traditional single-fiber-based BOTDA techniques. A 80-km-long sensing range, 1.73 MHz frequency accuracy and 2 m spatial resolution is experimentally demonstrated with 4000 trace averages.

中文翻译：

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基于单光纤的远端调制布里渊光时域分析


由引导光纤和传感光纤组成的环路配置是实现布里渊光时域分析 (BOTDA) 的常用方法，但对于某些物理上只有单根光纤可用的现场场景来说，实现这种方法是不切实际的。本文提出并实验证明了一种新型的基于单光纤的远端调制BOTDA，其中辅助光和脉冲从光纤近端注入，反向传播的探测光为通过调制来自远端的辅助光而产生。通过专门设计每个光波的频率和时间分布，布里渊相互作用仅发生在脉冲和探测光之间，同时避免了四波混合和瑞利跳动噪声等杂散效应，这构成了该技术的关键优势相对于传统的基于单光纤的 BOTDA 技术。通过 4000 条迹线平均值的实验证明了 80 公里长的传感范围、1.73 MHz 频率精度和 2 m 空间分辨率。