Stawska Hanna Izabela, Popenda Maciej Andrzej
Department of Telecommunications and Teleinformatics, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland.
Sensors (Basel). 2021 Mar 5;21(5):1803. doi: 10.3390/s21051803.
Long-period optical fiber gratings (LPGs) are one of the widely used concepts for the sensing of refractive index (RI) changes. Negative curvature hollow-core fibers (NCHCFs), with their relatively large internal diameters that are easy to fill with liquids, appear as a very interesting medium to combine with the idea of LPGs and use for RI sensing. However, to date, there has been no investigation of the RI sensing capabilities of the NCHCF-based LPGs. The results presented in the paper do not only address this matter, but also compare the RI sensitivities of the NCHCFs alone and the gratings. By modeling two revolver-type fibers, with their internal diameters reflecting the results of the possible LPG-inscription process, the authors show that the fibers' transmission windows shift in response to the RI change, resulting in changes in RI sensitivities as high as -4411 nm/RIU. On the contrary, the shift in the transmission dip of the NCHCF-based LPGs corresponds to a sensitivity of -658 nm/RIU. A general confirmation of these results was ensured by comparing the analytical formulas describing the sensitivities of the NCHCFs and the NCHCF-based LPGs.
长周期光纤光栅（LPG）是用于传感折射率（RI）变化的广泛应用概念之一。负曲率空心光纤（NCHCF）具有相对较大的内径，易于填充液体，似乎是一种非常有趣的介质，可与LPG概念相结合并用于RI传感。然而，迄今为止，尚未对基于NCHCF的LPG的RI传感能力进行研究。本文给出的结果不仅解决了这个问题，还比较了单独的NCHCF和光栅的RI灵敏度。通过对两种左轮手枪型光纤进行建模，其内径反映了可能的LPG写入过程的结果，作者表明光纤的传输窗口会随着RI的变化而移动，导致RI灵敏度变化高达-4411 nm/RIU。相反，基于NCHCF的LPG的传输凹陷的移动对应于-658 nm/RIU的灵敏度。通过比较描述NCHCF和基于NCHCF的LPG灵敏度的解析公式，确保了对这些结果的普遍确认。
