Mahakud R, Kumar J, Prakash O, Dixit S K
Appl Opt. 2013 Nov 1;52(31):7570-9. doi: 10.1364/AO.52.007570.
This paper presents an experiment and analysis on the factors affecting nonlinear evolution of Bragg wavelength with change in temperature in typical bare and embedded fiber Bragg grating-based (FBG) temperature sensors. The purpose of the study was to find the constants in the function required to evaluate temperature from Bragg wavelength shift. The temperature sensitivity of bare FBGs was found to increase with temperature elevation, and is different for FBGs written in different fiber types. The average temperature sensitivity increased by about 20% when the bare FBG temperature was elevated from 25°C to 525°C. The average temperature sensitivity of the embedded FBG sensor, investigated in the temperature range of 30°C-90°C, was a factor of 2-3 times larger than for bare FBG, depending on its fastened length with the substrate. Analytically, it is shown that the nonuniform behavior of temperature sensitivity in bare FBGs is the result of both the thermal expansion effect of the fiber and the temperature derivatives of the effective refractive index. The strain transfer and temperature coefficients of thermal expansion of the substrate affect the nonuniform behavior of temperature sensitivity in embedded FBG sensors.
本文针对典型的裸光纤布拉格光栅（FBG）温度传感器以及埋入式光纤布拉格光栅温度传感器，开展了关于温度变化影响布拉格波长非线性演化因素的实验与分析。该研究的目的是找出从布拉格波长偏移评估温度所需函数中的常数。研究发现，裸光纤布拉格光栅的温度灵敏度随温度升高而增加，且对于写入不同光纤类型的光纤布拉格光栅而言有所不同。当裸光纤布拉格光栅温度从25°C升高到525°C时，平均温度灵敏度提高了约20%。在所研究的30°C至90°C温度范围内，埋入式光纤布拉格光栅传感器的平均温度灵敏度比裸光纤布拉格光栅大2至3倍，这取决于其与基底的固定长度。从分析角度来看，裸光纤布拉格光栅温度灵敏度的非均匀行为是光纤热膨胀效应以及有效折射率温度导数共同作用的结果。基底的应变传递和热膨胀温度系数会影响埋入式光纤布拉格光栅传感器温度灵敏度的非均匀行为。
