基于薄芯光纤模态干涉技术的曲率光纤传感器

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 fiber-optic bending curvature sensor based on thin-core fiber modal interferometer

A new fiber-optic bending curvature sensor based on thin-core fiber modal interferometer is presented.In order to eliminate the environment effect on curvature measurement,one standard single-mode fiber with a segment of thin-core fiber is used for sensing,while the other without is used for reference.The insertion of thin-core optical fiber and single mode fiber core mode mismatch,resulting in high-order cladding modes are excited and interfere with the core mode to form an in-fiber modal interferometer.When a curvature applied to the thin-core fiber,the mode indices and the fiber length will change,and thus the transmission peaks will shift.Both ends of the fiber are connected to the translation stage.When adjusting the translation stage distance,the curvature of thin-core optical fiber is changed,leading to the transmission dip move to shorter wavelength.According to this distance,the bending curvature of the sensor can be measured.Experimental results show that this device has low loss,low cost and high sensitivity.