仅用一根局部微结构长周期光纤光栅实现温度与弯曲曲率的同时测量

提出并制作了一种具有微结构缺陷的局部微结构长周期光纤光栅,该光栅是用氢氟酸局部腐蚀长周期光纤光栅,在包层区域形成局部缺陷得到的.理论分析与实际制作表明,局部腐蚀会改变包层模的有效折射率调制,相当于在缺陷部分引入一个相移,在其光谱图上表现为在透射阻带中打开一个透射窗口,形成两个透射阻带和一个透射通带.在此基础上对其进行了传感实验,研究了两个透射阻带和透射通带的温度和弯曲特性.实验结果表明:透射通带和两透射阻带的温度灵敏度相同,均约为0.05 nm/?C;而透射通带的弯曲曲率灵敏度(约为-2.61 nm/m-1)小于透射阻带的弯曲曲率灵敏度(约为-4.71 nm/m-1),因此利用敏感矩阵,可以仅用一根光栅对弯曲曲率和温度双参量进行同时测量.

Simultaneous measurement of temperature and bending-curvature using a single local micro-structured longperiod fiber grating

A local micro-structured long-period fiber grating (LMSLPFG) is proposed and investigated experimentally. The LMSLPFG is fabricated by using hydrofluoric acid (HF) to partially etch a standard long-period fiber grating (LPFG), thereby forming a local defect in the cladding. The theoretical analysis and experimental results show that partially etching will change the effective refractive index modulation in the cladding mode, which equivalently introduces a phase shift into the part of defect and manifests, in the spectrogram, as openning a transmission window between the stopbands, forming two transmission stopbands and one transmission passband. On this basis we study the temperatures and bending characteristics of the two stopbands and one passband. The results show that the temperature sensitivities of the two stopbands and one passband are all approximately 0.05 nm/℃; the bending sensitivity of the passband (2.61 nm/m^-1) is less than those of two stopbands (4.71 nm/m^-1). Thus by using the sensitive matrix, we can simultaneously measure the curvature and temperature, with only one grating used.