提出一种在线型光纤法布里-珀罗折射率传感器。传感器由空芯光子晶体光纤两端熔接单模光纤而成。理论分析并实验验证了其折射率传感特性。结果表明, 干涉条纹对比度随溶液折射率的增加而减小, 与理论模拟一致。提出利用标准差解调方法对干涉谱进行分析, 标准差解调方法具有更好的线性度和准确性, 可靠性更高, 便于编程实现自动化、快速的数据分析和溶液折射率的实时检测。

An in-line fiber Fabry-Perot (F-P) refractive index (RI) sensor is proposed. The sensor is formed by splicing both ends of a short section of hollow-core photonic crystal fiber (HCPCF) to single mode fibers (SMFs). RI response of the sensor is analyzed theoretically and demonstrated experimentally. Results show that the fringe contrast of interference spectrum decreases as the external RI increases, which is consistent with theory. A new demodulation method based on standard deviation analysis is proposed. The method provides the better linearity and accuracy, higher reliability. Moreover, it’s convenient for automatic and fast signal processing in real-time monitoring of RI.