我们设计并制作了一种基于 Mach-Zehnder干涉的高灵敏折射率传感器, 其结构由两个光纤纤芯偏移的熔接结经包层腐蚀后组成。首先, 利用商用的光纤熔接机在单模光纤上制作两个光纤纤芯偏移的熔接结; 然后, 将光纤化学腐蚀获得细薄的光纤包层, 则光纤倏逝场与周围介质强烈相互作用, 即制作出 Mach-Zehnder干涉型高灵敏折射率传感器。实验结果表明, 制作的长度为 10 mm、直径为 13.2 μm的 Mach-Zehnder干涉型折射率传感器, 在折射率 1.333~1.368 5和 1.368 5~1.386范围内, 其传感灵敏度分别高达 1 288.05和 2 118.26 nm/RIU。该传感器具有高灵敏度、结构紧凑、制作简单和低成本的优势。

We propose and fabricate a high-sensitivity Mach-Zehnder interferometer (MZI) refractive index (RI) sensor formed by concatenating two Core-offset Joints (COJs) in a cladding-etched fiber. The two COJs are fabricated in a single-mode fiber by using a commercial fiber fusion splicer. Then, the fiber cladding is thinned by chemical etching, and high-sensitivity MZI RI sensor is formed owing to the strong interaction of the evanescent field of the thin fiber and the surrounding medium. Experimental results show that, for the MZI with a length of 10 mm and a fiber diameter of 13.2 μm, its RI sensitivities are up to 1 288.05 and 2 118.26 nm/RIU in the RI ranges of 1.333~1.368 5 and 1.368 5~1.386, respectively. The sensor reveals the advantages of high sensitivity, compact size, simple fabrication, as well as low cost.