A theoretical and experimental study on curvature sensing using a Brillouin optical time-domain analyzer based on the ring-core fiber (RCF) is reported. The Brillouin gain spectrum of the RCF is investigated, and the Brillouin frequency shift (BFS) dependence on temperature and strain is calibrated. We theoretically analyze the fiber bending-induced BFS and peak Brillouin gain variation for the RCF through a numerical simulation method, and the RCF is revealed to have a high curvature sensitivity. Distributed curvature sensing is successfully demonstrated, with the bending radius ranging from 0.5 to 1.5 cm, corresponding to a BFS variation from 32.90 to 7.81 MHz. The RCF takes advantage of great bending loss resistance, and the maximum macrobending loss at the extreme bending radius of 0.5 cm is less than 0.01 dB/turn. Besides, the peak Brillouin gain of the RCF is discovered to vary significantly in response to fiber bending, which is expected to be another parameter for distributed curvature determination. The results imply that the RCF is a promising candidate for highly sensitive distributed curvature measurement, especially in sharp bending circumstances.

中文翻译：

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基于抗弯曲损耗环芯光纤的分布式曲率传感

报告了使用基于环芯光纤 (RCF) 的布里渊光学时域分析仪进行曲率传感的理论和实验研究。研究了 RCF 的布里渊增益谱，并校准了布里渊频移 (BFS) 对温度和应变的依赖性。我们通过数值模拟方法从理论上分析了光纤弯曲引起的 BFS 和峰值布里渊增益变化，发现 RCF 具有高曲率敏感性。成功展示了分布式曲率传感，弯曲半径范围从 0.5 到 1.5 cm，对应于从 32.90 到 7.81 MHz 的 BFS 变化。RCF利用抗弯曲损耗大的优势，0.5cm极限弯曲半径下的最大宏弯损耗小于0.01dB/turn。除了，发现 RCF 的峰值布里渊增益随光纤弯曲而显着变化，这有望成为分布式曲率确定的另一个参数。结果表明，RCF 是高度敏感的分布式曲率测量的有希望的候选者，尤其是在急剧弯曲的情况下。