A waist-enlarged taper Michelson interferometric trace fluoride-ion sensor based on silver film encapsulated the head face of thin-core fiber (TCF) is proposed and presented. The waist-enlarged taper is spliced between the single-mode fiber and the TCF to realize the optical splitter. The aluminium doped zinc oxide is coated on the outside surface of TCF as the fluoride-ion sensing membrane. Silver film on the head face of TCF is to enhance light reflection. The refractive index of the sensing membrane is changed by the adsorption of fluoride-ion, and then the monitoring interference dip of the sensor changes accordingly. Thus, the fluoride-ion concentration can be determined by the corresponding wavelength shift. The sensor can be used to detect trace fluoride-ion in the range of 0–50.0 ppb with an average sensitivity of 60.02 pm ppb⁻¹. When the concentration is in the range of 0.01–0.10 ppb, the linearity is 0.998, and the sensitivity can be 3341.23 pm ppb⁻¹. In the 0.3–2.0 ppb concentration range, the linearity is about 0.975, and the sensitivity can reach 404.75 pm ppb⁻¹. As the concentration ranging from 5.0 to 50.0 ppb, the linearity is about 0.982 with the good sensitivity (23.75 pm ppb⁻¹). The response time (about 40 s) of the sensor has been determined. The sensor has the advantages of high sensitivity, excellent selectivity, simple structure and rapid response, and can be put into the application for the trace fluoride-ion detection in water.

提出并提出了一种基于银膜封装的细芯光纤 (TCF) 端面的腰部放大锥形迈克尔逊干涉痕量氟离子传感器。在单模光纤和TCF之间拼接腰扩锥体，实现分光器。铝掺杂氧化锌涂覆在TCF的外表面上作为氟离子传感膜。TCF头面上的银膜是为了增强光反射。由于氟离子的吸附，传感膜的折射率发生变化，传感器的监测干扰倾角也随之发生变化。因此，氟离子浓度可以通过相应的波长偏移来确定。该传感器可用于检测 0–50.0 ppb 范围内的痕量氟离子，平均灵敏度为 60.02 pm ppb^-1。当浓度在0.01-0.10 ppb范围内时，线性为0.998，灵敏度可达3341.23 pm ppb ^-1。在0.3-2.0 ppb浓度范围内，线性度约为0.975，灵敏度可达404.75 pm ppb ^-1。当浓度范围为5.0至50.0 ppb时，线性度约为0.982，具有良好的灵敏度（23.75 pm ppb ^-1）。传感器的响应时间（约 40 秒）已确定。该传感器具有灵敏度高、选择性好、结构简单、响应快等优点，可应用于水中痕量氟离子的检测。