低温环境下FBG温度传感特性研究

Study on Temperature Sensing Characteristics of FBG in Low Temperature Environment

在低温环境中,光纤光栅(Fiber Bragg Grating,FBG)材料的热膨胀系数和热光系数会发生改变,从而影响其温度传感特性。文章通过实验研究了裸光纤光栅传感器和黄铜管封装的光纤光栅传感器在低温下的温度传感特性。结果表明,在80~300 K温度范围,裸FBG温度传感器的灵敏度为6.43 pm/K,线性度为0.974,在80~230 K温度范围,温度与光纤光栅的中心波长呈现非线性关系;黄铜管封装的FBG温度传感器,在整个温度范围内灵敏度可达26 pm/K,线性度为0.996,较裸FBG温度传感器均有较大提升。对比实验表明,对光纤光栅进行封装,可以提高其温度灵敏度和线性度,改善温度传感特性。

In low temperature environment,the thermal expansion coefficient and thermal optical coefficient of fiber Bragg grating(FBG)material will change,which will affect its temperature sensing characteristics.In this paper,the temperature sensing characteristics of bare FBG sensors and brass tube-encapsulated FBG sensors were studied experimentally.The results show that in the temperature range of 80~300 K,the sensitivity of the bare FBG temperature sensor is 6.43 pm/K and the linearity is 0.974,and the relationship between temperature and fiber grating center wavelength is nonlinear in the temperature range of 80~230 K.The brass tube-encapsulated FBG temperature sensor has a sensitivity of 26 pm/K and a linearity of 0.996 in the whole temperature range,which is greatly improved compared with that of the bare FBG temperature sensor.Comparative experiments show that the encapsulating of fiber Bragg grating can not only improve its temperature sensitivity and linearity,but also improve its temperature sensing characteristics.