基于弯曲光纤的折射率传感器研究

Investigation of optic-fiber refractive index sensor based on bent fiber

以标准单模光纤（SMF）在弯曲后出现的模间干涉为基础,设计了一种新型的折射率光纤传感器,并分别对环境折射率和温度进行了实验探究。光纤折射率传感器制作工艺简单,传感区域由一根具有特定弯曲半径的半圆形标准SMF构成。选取1 510-1 590nm波段为监测范围,选取裸光纤弯曲半径R=4.5mm;在常温下,通过改变传感区周边环境折射率从1.328 8增长到1.372 1,得出两个干涉共振峰的折射率灵敏度分别为147.602和125.459nm/RIU。当环境温度从23到33℃增长时,两峰的温度灵敏度分别为-280和-460pm/℃;而在低于23℃的情况下,温度的变化对传感器没有明显的影响,可以实现温度不敏感的折射率测量。本文传感器制作方法简易、架构简单和灵敏度高,可适用于生化检测、环境检测等领域。

This paper proposes a new type of optic-fiber sensor,which is based on intermodal interference when a standard single-mode fiber is bendt,and experimentally confirms it can be used in refractive index（RI）measurement and temperature measurement.The sensor has a very simple structure,and the sensing area consists of a semicircle standard single-mode fiber with a certain bending radius.The radius of bare fiber is classified as 4.5mm.In the band from 1 510 nm to 1 590 nm,when the surrounding RI increases from 1.328 8to 1.372 1,the RI sensitivities of the two response dips are 147.602nm/RIU and125.459nm/RIU respectively at normal temperature.As well,when the environment temperature changes from 23℃to 33℃,the temperature sensitivities of the two response dips are-280pm/℃and-460pm/℃,respectively.But when temperature is less than 23℃,the change of temperature has almost no obvious effect on sensor,so it can realize RI measurement with no influence by temperature at normal temperature.