本文基于气体的窄带光吸收特性 ,研究了 SO2 气体浓度与载波光强的关系 ,在此基础上 ,设计了一种检测该气体浓度的差动光纤传感器及其系统 ,对改善仪器精度等特性指标的主要因素进行分析。实验结果表明该仪器具有较高的灵敏度和精度。 In this paper, the relationship between the concentration of SO2 gas and the light intensity of the carrier was studied based on the narrow-band light absorption characteristics of the gas. Based on this, a differential optical fiber sensor and its system for detecting the concentration of the gas were designed. The main factors for analysis. The experimental results show that the instrument has high sensitivity and accuracy.