测量液体折射率与浓度的光纤光栅传感器

基于长周期光纤光栅的耦合模理论,从简化的三层光纤模型出发,研究了外界环境折射率变化时长周期光纤光栅传输谱的变化,并对氯化钠溶液的浓度和折射率进行了验证。实验结果发现,长周期光纤光栅的谐振波长与氯化钠浓度的变化近似成线性关系,而与折射率成二次曲线关系,这与数值模拟的结果一致。采用长周期光纤光栅测量液体的浓度和折射率的方法结构简单,且传感信号属于波长解调,避免了光强波动及光纤损耗的影响,整个传感系统全光纤化,能够实现对环境介质的在线、实时、快速、精确测量,还可用于特殊测量场合,实现远程遥测功能。

Fiber grating sensor for measurement of solution refractive index and concentration

Based on the coupling theory and the simplified three-layed model,the influence of the surround refractive index change upon an long period optical grating(LPFG)is studied,its characteristics such as resonant wavelength and peak loss in detail is analyzed.Relation of wavelength shifts in the LPFG and different concentrations of sodium chloride solution is approximate linear,which is agree with the theoretical results.This method is simple,and the signal is wavelength modulated,which is not reflected by the fluctuation of light intensity and the fiber loss.The sensing system is all light transmitted by fiber.It not only can on-line measure,realize rapid accurate measurement for target medium,but also can be used in some special situations and easily realize long distance measurement.