基于偏芯结构的光纤弯曲传感器及其特性研究

Fiber-optic curvature sensor based on a core-offset structure

提出了一种基于偏芯熔接(COJ)结构的光纤弯曲传感器。传感器利用COJ结构,将部分纤芯光耦合到包层中形成包层模,在输出端与纤芯模进行耦合形成干涉,并通过探测输出光谱的波长漂移对曲率进行探测。理论和实验表明,本文结构的弯曲传感器具有较好的弯曲灵敏度以及较好的线性响应曲线,对长为55.6mm的传感器,其弯曲灵敏度为-6.9nm/m-1;传感器长度会影响传感器的弯曲灵敏度,长度越长,弯曲灵敏度越大。

A fiber-optic curvature sensor based on a core-offset structure has been proposed and demonstrated in this paper. Here two core-offset jointing points have been inserted in the sensor. The first coreoffset jointing point is used to excite the cladding modes and the second one is used as the interference point. We fix the core-offset structure based curvature sensor by two fiber holders which can be controlled precisely to control the bending curvature of the sensor. The fiber holder is adjusted for 20 bLm per time with the total adjusted distance of 200μm in this experiment. The experimental results show that the curvature sensor is very sensitive to bending change and the transmission spectrum of the sensor will shift to blue wavelength with the increasing of the bending curvature. The measured curvature sensitivity is -6.9 nm/m 1 with the sensor length of 55.6 mm. In order to study the influence of the fiber length, we fabricated three sensors with different fiber lengths. The experimental results show that the curva- ture sensitivity can be influenced by the length of the sensor and the curvature sensitivity will be in- creased with the increasing of the length of the sensor.