A fiber optical curvature sensor comprising a concave‐heterotypic cascaded fiber structure built into Sagnac loop is demonstrated experimentally. A section of multimode fiber is sandwiched between the single mode fiber and polarization maintaining fiber in order to construct the concave‐heterotypic cascaded fiber structure. The concave structure presented is used to effectively excite guided modes. The spectra of the proposed bending sensor will shift toward long wavelength with curvature. The measured the curvature sensitivity of 11.6 nm/m⁻¹ has been achieved. The proposed curvature sensor characterizes cost‐efficient, simple fabrication process and can be used for health monitoring in civil engineering.

中文翻译：

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基于凹异型级联光纤Sagnac干涉仪的光纤曲率传感器

实验证明了一种光纤曲率传感器，该传感器包括内置于Sagnac环中的凹异型级联纤维结构。将多模光纤的一部分夹在单模光纤和保偏光纤之间，以构造凹异型级联光纤结构。所呈现的凹面结构用于有效地激发引导模式。所提出的弯曲传感器的光谱将随着曲率向长波长移动。测得的曲率灵敏度达到了11.6 nm / m ^-1。提出的曲率传感器具有成本效益高，制造工艺简单的特点，可用于土木工程中的健康监测。