通过分析光纤布拉格光栅(FBG)光谱响应和指数衰荡的动态变化,探究内置FBG光纤环形衰荡腔的温度传感系统性能。建立FBG环形衰荡腔的理论模型,研究FBG透射谱中心波长与指数衰荡时间随温度的变化及其动态的演变过程,搭建1551.13 nm脉冲激光的FBG环形衰荡腔温度传感系统对其进行了实验验证,数值模拟结果与实验结果相吻合。实验结果表明,所提系统在低温环境-40 ℃下有良好的重复性、稳定性,测量分辨率高达0.05 ℃,温度灵敏度为0.02501/(μs?℃),FBG中心波长的灵敏度为0.00248/(μs·pm)。

In this study, the temperature sensing system performances of a fiber loop ring-down cavity with a fiber Bragg grating (FBG) are investigated by analyzing the spectral response of an FBG and the dynamic variation of an exponential decay. A theoretical FBG loop ring-down cavity model is established to investigate the relationships of the central wavelength of the FBG transmission spectrum and the exponential decay time with temperature change as well as their dynamic evolution procedures. They are experimentally tested by building a temperature sensing system integrated with a fiber loop ring-down cavity with an FBG and 1551.13 nm pulsed laser. The mathematical simulation results agree well with the experimental results, which show that the proposed system has perfect repeatability and stability under the low temperature conditions of -40 ℃. Specifically, the measurement resolution achieved is 0.05 ℃, the sensitivity of temperature is 0.0025/(μs·℃), and the sensitivity of FBG central wavelength is 0.00248/(μs·pm).