Abstract An optic fiber refractive index (RI) sensor based on SMF-MMF-TMCF-SMF (SMTmS) structure is proposed. The MMF segment is introduced and confirmed theoretically and experimentally to act as an efficient optical coupler to launch the light from the center core to the cladding. Experimental results demonstrate that SMTmS is highly sensitive (1435.76 nm/RIU) to low surrounding RI in the range of 1.3330–1.3451. The temperature sensing has been implemented and the total wavelength shift of only 1.83 nm is achieved for the range of 30 °C–100 °C, implying a relatively low temperature cross-sensitivity of 2.01 × 10−5 RIU/°C. The developed sensor with high RI sensitivity and low temperature cross-sensitivity could be rather suitable and applicable in the fields of seawater sensing and environmental monitoring.

中文翻译：

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基于SMF-MMF-TMCF-SMF结构的低温敏折射率干涉仪

摘要 提出了一种基于SMF-MMF-TMCF-SMF(SMTmS)结构的光纤折射率(RI)传感器。MMF 段被引入并在理论上和实验上证实，作为一种有效的光耦合器，将光从中心纤芯发射到包层。实验结果表明，SMTmS 对 1.3330–1.3451 范围内的低周围 RI 高度敏感 (1435.76 nm/RIU)。已经实施了温度传感，并且在 30°C–100°C 的范围内仅实现了 1.83 nm 的总波长偏移，这意味着相对较低的温度交叉灵敏度为 2.01 × 10-5 RIU/°C。研制的具有高RI灵敏度和低温交叉灵敏度的传感器在海水传感和环境监测领域具有较好的适用性和适用性。