Abstract This paper focuses on four structural parameters of reflective microfiber coupler (MFC), including taper length, taper width, coupling length, and coupling diameter. The influences of those parameters upon the performance of MFC are identified through simulation and are justified through mathematical and coupling theory. Subsequently, refractive index (RI) sensing experiments were conducted to characterize the performance of MFCs with different structural parameters, thereby verifying the simulation results. The most significant result is the correlation between the sensitivity and coupling diameter, which demonstrates that the general view, which considers the correlation monotonically negative, is partially correct. The optimal coupling diameter, for which MFC achieves the highest sensitivity, was shown to be approximately 25 μm. Due to the optimal coupling diameter, the sensitivity is tripled to 11780.5 nm/RIU for RI values from 1.33 to 1.36. The developed sensor is expected to become a reasonable choice when sensitive RI measurements are required.

中文翻译：

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具有最佳直径的反射式微光纤耦合器，用于超灵敏折射率传感

摘要 本文重点研究了反射式微光纤耦合器（MFC）的锥长、锥宽、耦合长度和耦合直径四个结构参数。这些参数对 MFC 性能的影响通过仿真确定，并通过数学和耦合理论进行验证。随后，进行了折射率（RI）传感实验以表征具有不同结构参数的 MFC 的性能，从而验证模拟结果。最重要的结果是灵敏度和耦合直径之间的相关性，这表明认为相关性单调为负的一般观点是部分正确的。MFC 实现最高灵敏度的最佳耦合直径约为 25 μm。由于最佳耦合直径，当 RI 值从 1.33 到 1.36 时，灵敏度增加了两倍，达到 11780.5 nm/RIU。当需要敏感的 RI 测量时，开发的传感器有望成为一个合理的选择。