Standard multimode optical fibers normally support transmission over some 100 modes. Large differences in the propagation constant and the spatial distribution of distinct modes degrade the performance of phase-sensitive optical time-domain reflectometry measurements. In this work, we present a new realization of a coherent time-domain interrogation technique using single-mode operation in multimode fibers. We demonstrate effectively distributed strain sensing on three different multimode optical fibers. Up to 4 km of multimode fiber has been correctly interrogated, featuring a spatial resolution of 20 cm.

中文翻译：

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多模光纤中的频率扫描相敏光时域反射法询问

标准的多模光纤通常支持约100种模式的传输。传播常数和不同模式的空间分布的较大差异会降低相敏光学时域反射仪测量的性能。在这项工作中，我们提出了一种在多模光纤中使用单模操作的相干时域询问技术的新实现。我们展示了在三种不同的多模光纤上的有效分布应变传感。正确地询问了长达4 km的多模光纤，其空间分辨率为20 cm。