Abstract. We report a simple refractive index (RI) sensor based on a twin-hole fiber (THF). The THF is fused with the single-mode fiber to realize sensing by the multimode interference. The mode transmission characteristics in the THF are numerically investigated. In the sensing experiment, when the surrounding RI changes, the wavelength shift of the transmission spectrum shows approximate linearity in the low RI region and nonlinearity in the high RI region. When a THF with the length of 10 mm is used, the highest sensitivity can be up to 1351 nm / RIU in the RI range from 1.430 to 1.445. Moreover, the effect of the temperature on the transmission spectrum relative to the RI is much smaller when the external temperature changes from 30°C to 80°C.

中文翻译：

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基于双孔光纤中多模干涉的折射率传感器

摘要。我们报告了一种基于双孔光纤 (THF) 的简单折射率 (RI) 传感器。THF与单模光纤融合，通过多模干涉实现传感。数值研究了 THF 中的模式传输特性。在传感实验中，当周围RI变化时，透射光谱的波长漂移在低RI区域呈现近似线性，在高RI区域呈现非线性。当使用长度为 10 mm 的 THF 时，在 RI 范围从 1.430 到 1.445 时，最高灵敏度可达 1351 nm / RIU。此外，当外部温度从 30°C 变为 80°C 时，相对于 RI，温度对透射光谱的影响要小得多。