We present a theoretical analysis into the fundamental physical mechanisms contributing to backscattering in hollow-core antiresonant fibers. We consider Rayleigh scattering originating from the hollow regions of the fiber, which may be filled with gases, Rayleigh scattering from within the glass membranes, as well as the contribution from scattering at the glass surfaces. We derive expressions for the backscattering coefficient into any specified guided mode for an arbitrary excitation. These lead to general scaling relations with the core size and wavelength, which are found to be the key parameters for backscattering, regardless of the exact antiresonant geometry. For a nested antiresonant hollow-core fiber with a core diameter of 35 µm, the only antiresonant fiber geometry for which the experimental data are available in the literature, we find that the surface-scattering limited backscattering coefficient of the fundamental mode into itself is nearly 40 dB below that of a single mode fiber, in good agreement with recently published measurements.

中文翻译：

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空芯反谐振光纤背向散射的理论分析

我们对空芯反谐振光纤中产生反向散射的基本物理机制进行了理论分析。我们考虑源自纤维中空区域的瑞利散射，其中可能充满气体，来自玻璃膜内的瑞利散射，以及来自玻璃表面散射的贡献。我们将反向散射系数的表达式推导出为任意激励的任何指定引导模式。这些导致与纤芯尺寸和波长的一般缩放关系，发现它们是反向散射的关键参数，而不管确切的反谐振几何形状。对于纤芯直径为 35 µ的嵌套反谐振空芯光纤m 是文献中唯一可以获得实验数据的反谐振光纤几何结构，我们发现基模自身的表面散射限制后向散射系数比单模光纤低近 40 dB，与最近公布的测量结果。