Abstract The influence of core radius on refractive index sensitivity of long period fiber grating (LPFG) sensor has been studied theoretically for the first time, and a new method to fabricate LPFG sensor with high sensitivity is proposed. The structure and parameters of the optical fiber, the period of the gratings, and the coupling order of the cladding modes are all held consistent in the process of studying the change of the core radius. The resonant wavelength of LPFG sensor shifts with changes in the external environment, which is simulated by the transfer matrix method. The sensitivity of LPFG sensor is enhanced by more than 200 times when the core radius increases from 3.1 to 5.1 μm. The results show that LPFG sensors with larger core radii have higher sensitivity. Selecting a fiber with a large core radius to fabricate LPFG sensors is proposed as a method to improve the sensitivity of these devices. This new simple and effective method is expected to be widely used in the manufacture of high sensitivity LPFG sensors in the future.

中文翻译：

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纤芯半径对长周期光纤光栅传感器影响的理论分析

摘要 首次从理论上研究了纤芯半径对长周期光纤光栅(LPFG)传感器折射率灵敏度的影响，提出了一种制备高灵敏度LPFG传感器的新方法。在研究纤芯半径变化的过程中，光纤的结构和参数、光栅的周期、包层模式的耦合阶次都保持一致。LPFG 传感器的谐振波长随外部环境的变化而变化，这是通过传递矩阵方法模拟的。当纤芯半径从 3.1 μm 增加到 5.1 μm 时，LPFG 传感器的灵敏度提高了 200 倍以上。结果表明，纤芯半径较大的LPFG传感器具有更高的灵敏度。建议选择具有大纤芯半径的光纤来制造 LPFG 传感器，作为提高这些设备灵敏度的方法。这种简单有效的新方法有望在未来广泛应用于高灵敏度LPFG传感器的制造中。