采用聚酰胺酸层的高灵敏度长周期光纤光栅温度传感器

设计并论证了一种高灵敏度的长周期光纤光栅（LPG）温度传感器。将LPG的包层腐蚀，封装进金属外壳使LPG保持恒定拉力，再密封进盛满聚酰胺酸（PAA）的试管中，其中聚酰胺酸热光系数较大，作为感温材料。测试并讨论了使用不同折射率的聚酰胺酸与不同包层直径的LPG时，LPG共振波长随温度变化的漂移。结果显示，对于一个直径已知的特定LPG，当使用较大折射率的聚酰胺酸时，LPG温度传感器的灵敏度变高。对于使用相同折射率聚酰胺酸的LPG，随着LPG的包层直径减小，LPG温度传感器的灵敏度变高。实验制作的LPG温度传感器的灵敏度为1.26 nm/℃，约为普通LPG制作的传感器的10倍，以及普通FBG制作的传感器的100倍。这种新传感器在2~35℃线性度为99.80%，这提高了传感器的潜在应用，特别是在生物医学检测，海洋监测等这些温度范围接近室温的领域。

Highly sensitive LPG temperature sensor employing polyamic acid-coating

A highly sensitive long period fiber grating(LPG) temperature sensor was designed and demonstrated. Cladding of the LPG was etched and encapsulated in metal to maintain constant strain, then was sealed in a test tube containing polyamic acid(PAA), which had a relatively large thermo-optic coefficient as a temperature-sensitive material. The resonance wavelength shifted with temperature for different PAA refractive index values and different LPG cladding diameters were measured and discussed. The results show that the sensitivity of the LPG temperature sensor becomes higher when the refractive index of PAA becomes larger for a certain LPG of determined diameter. Additionally the sensitivity of the LPG temperature sensor becomes higher when the cladding diameter of the LPG decreases for a determined refractive index of PAA. A sensitivity of 1.26 nm/℃ was achieved for this improved LPG temperature sensor, ten times greater than that of the sensor made of common LPG and 100 times greater than that made of common fiber Bragg grating (FBG). This new sensor exhibits good linearity of 99.80% at temperatures of 2-35℃, which improves its potential application for biomedical measurement and ocean detection, where the temperature range of interest is close to room temperature.