提出了一种基于微结构法布里-珀罗干涉仪(MS-FPI)的光纤光栅(FBG)脉搏波解调方法。所提出的MS-FPI由单模光纤和光子晶体光纤(PCF)熔接而成, 通过特殊的工艺在熔接端面形成微气泡构成布里-珀罗(F-P)腔, 其尺寸约为48 μm。该MS-FPI经再涂覆后具有较好的机械强度, 可作为纱线织入织物。其干涉谱在弯曲直径4 cm范围内, 基本保持不变, 且具有极低的温度灵敏度, 适合作为解调滤波器。对该波长解调方法进行理论分析和实验研究,结果表明,所设计的解调系统在FBG脉搏波范围内可实现线性解调, 具有较好的测量重复性, 解调灵敏度约为43 mV/pm; 所解调出的脉搏波与商用解调仪的结果一致, 通过与光电容积脉搏波的对比, 证明了所设计系统解调脉搏波的正确性。

A demodulated method for fiber Bragg grating (FBG) pulse wave is proposed based on micro-structure Fabry-Perot interferometer (MS-FPI). The proposed MS-FPI is fabricated by splicing single mode fiber and photonic crystal fiber (PCF), and the micro-bubble structure is formed near the splicing end face by the special technology to constitute the Fabry-Perot (F-P) cavity, whose size is about 48 μm. In order to increase mechanical strength, the MS-FPI is coated again and thus can be woven into the fabric as yarn. Its interference spectrum remains nearly unchanged even its bending diameter is up to 4 cm. Besides, it also has very low temperature sensitivity, suitable as a demodulator filter. The proposed demodulated method is analyzed theoretically and studied experimentally. The results indicate that the designed demodulated system achieves linear demodulation in the range of the FBG pulse wave and has better measurement repeatability. The demodulated sensitivity is about 43 mV/pm. The demodulated pulse wave is consistent with the result of the commercial interrogator. By comparing with the photoplethysmography, the correctness of the pulse wave demodulated by designed system is proved.