We propose a compact assemble-easy cost-effective vector bending sensor consisting of a short section of single stress-applying fiber (SSAF) spliced between two standard single-mode fibers (SMFs). The SSAF is specially designed by introducing a stress-applying part (SAP) into the cladding to achieve the asymmetrical geometry. Because of the mode field mismatch between the SMF and the SSAF, the cladding mode is effectively excited, which is sensitive to the bending and has orientation-dependence. Due to the large effective refractive index difference between the core and cladding mode, a compact dual-mode interferometer can be achieved with a thousands-micron-long structure. When the fiber is bent, the mode fields and the effective refractive indices will be modified, and accordingly, the direction-dependent interference spectral shift is observed. Owing to the well-designed SSAF structure, the cost-effective vector bending sensor can be easily realized by a simple sandwich structure without extra complex alignment procedures or fiber grating inscription. We experimentally verify the vector bending property. The maximum sensitivity of 2.04 nm/m ⁻¹ is obtained, and the experimental results match well with the simulations. Our proposed device is compact, easy to assemble, and cost-effective, which is promising in the field of vector bending measurement.

中文翻译：

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基于单应力光纤的紧凑型鲁棒矢量弯曲传感器

我们提出了一种紧凑，易于组装，具有成本效益的矢量弯曲传感器，该传感器由一小段单应力施加光纤（SSAF）组成，该光纤拼接在两个标准单模光纤（SMF）之间。SSAF是通过将应力施加部件（SAP）引入覆层中以实现不对称几何形状而专门设计的。由于SMF和SSAF之间的模式场不匹配，因此有效激发了包层模式，该模式对弯曲敏感并且具有方向依赖性。由于纤芯和包层模式之间的有效折射率差很大，因此可以用数千微米长的结构实现紧凑的双模干涉仪。当光纤弯曲时，模场和有效折射率将被修改，因此，可以观察到与方向有关的干涉光谱偏移。由于设计合理的SSAF结构，可以通过简单的夹心结构轻松实现具有成本效益的矢量弯曲传感器，而无需额外的复杂对准程序或光纤光栅标记。我们通过实验验证了矢量弯曲特性。最大灵敏度2.04 nm / m 获得^-1，并且实验结果与仿真非常吻合。我们提出的设备紧凑，易于组装且具有成本效益，这在矢量弯曲测量领域很有希望。