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为了降低光纤布拉格光栅(FBG)中心波长对温度变化的敏感度,提出了一种FBG温度补偿新方法。用石英玻璃管对栅区包层被部分腐蚀的FBG进行罐状封装,内部填充具有一定折射率和负热光系数的液体以充当环境包层。利用液体包层热光效应影响FBG中心波长紫移的特性补偿光纤热膨胀和热光效应产生的红移特性,提高了FBG中心波长的温度稳定性,并且在25~55℃的局部温度范围内获得了0.002 2nm/℃的温度系数,使FBG中心波长的温度稳定性提高了近5倍,验证了方法的可行性。理论与实验研究表明,通过减小FBG包层厚度或选择具有较大折射率和热光系数的封装液体,可进一步提高封装后的FBG的温度稳定性。这种温度补偿方法简单可行,避免了胶粘材料封装固化过程中的光栅啁啾,拓展了FBG在光纤传感和通信中的功能化应用。
In order to reduce the sensitivity of fiber Bragg grating (FBG) center wavelength to temperature change, a new method of FBG temperature compensation is proposed. A partially etched FBG with a gate region cladding is pot-sealed with a quartz glass tube and internally filled with a liquid having a certain index of refraction and a negative thermal coefficient to act as an environmental cladding. The red shift characteristics caused by the thermal expansion and thermo-optic effect of the FBG are affected by the effect of the thermal envelope of the liquid cladding on the violet shift of the FBG center wavelength, which improves the temperature stability of the FBG center wavelength and is obtained in the local temperature range of 25-55 ℃ The temperature coefficient of 0.002 2nm / ℃ increased the temperature stability of the center wavelength of FBG almost five times, which proves the feasibility of the method. Theoretical and experimental studies show that the temperature stability of the encapsulated FBG can be further improved by reducing the thickness of the FBG cladding or selecting the encapsulating liquid with larger refractive index and thermal coefficient. The temperature compensation method is simple and feasible, avoids the grating chirp in the curing process of the adhesive material, and expands the functional application of the FBG in optical fiber sensing and communication.