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提出了一种新的基于薄芯光纤模态干涉技术的光纤曲率传感器。在单模光纤的中间部分插入薄芯光纤用于传感光路,没有插入薄芯光纤的单模光纤用于参考光路,以消除环境对曲率测量的影响。由于插入的薄芯光纤和单模光纤纤芯失配,导致包层的高次模被激发,并与纤芯模在单模光纤内形成干涉。当改变薄芯光纤的曲率时,沿纤芯和包层传播的模态和光纤长度会发生改变,使得干涉谷峰发生平移。将传感光纤的两端固定的平移台上,当调节平移台距离时,薄芯光纤的曲率发生改变,导致干涉谷峰向短波方向平移。通过观察谷峰的平移距离可以实现曲率的传感测量。实验表明,该装置具有低损耗、低成本和高灵敏度的特点。
A new fiber curvature sensor based on the thin-core fiber mode interference technique is proposed. Inserting a thin core fiber in the middle of a single mode fiber for sensing the optical path, a single mode fiber without a thin core fiber is used for the reference beam path to eliminate the influence of the environment on the curvature measurement. Due to the mismatch between the inserted thin core fiber and the single mode fiber core, the higher order mode of the cladding is excited and interferes with the core mode within the single mode fiber. When changing the curvature of a thin core fiber, the modes and fiber lengths that propagate along the core and cladding change so that the interfering valley peaks shift. When both ends of the sensing optical fiber are fixed on the translation stage, when the distance between the translation stages is adjusted, the curvature of the thin core optical fiber changes, causing the interference peak to translate to the short-wave direction. The sensing of curvature can be measured by observing the translational distance of the valley peak. Experiments show that the device has the characteristics of low loss, low cost and high sensitivity.