Over the past few years, progress in hollow-core optical fiber technology has reduced the attenuation of these fibers to levels comparable to those of all-solid silica-core single-mode fibers. The sustained pace of progress in the field has sparked renewed interest in the technology and created the expectation that it will one day enable realization of the most transparent light-propagating waveguides ever produced, across all spectral regions of interest. In this work we review and analyze the various physical mechanisms that drive attenuation in hollow-core optical fibers. We consider both the somewhat legacy hollow-core photonic bandgap technology as well as the more recent antiresonant hollow-core fibers. As both fiber types exploit different guidance mechanisms from that of conventional solid-core fibers to confine light to the central core, their attenuation is also dominated by a different set of physical processes, which we analyze here in detail. First, we discuss intrinsic loss mechanisms in perfect and idealized fibers. These include leakage loss, absorption, and scattering within the gas filling the core or from the glass microstructure surrounding it, and roughness scattering from the air–glass interfaces within the fibers. The latter contribution is analyzed rigorously, clarifying inaccuracies in the literature that often led to the use of inadequate scaling rules. We then explore the extrinsic contributions to loss and discuss the effect of random microbends as well as that of other perturbations and non-uniformities that may result from imperfections in the fabrication process. These effects impact the loss of the fiber predominantly by scattering light from the fundamental mode into lossier higher-order modes and cladding modes. Although these contributions have often been neglected, their role becomes increasingly important in the context of producing, one day, hollow-core fibers with sub-0.1-dB/km loss and a pure single-mode guidance. Finally, we present general scaling rules for all the loss mechanisms mentioned previously and combine them to examine the performance of recently reported fibers. We lay some general guidelines for the design of low-loss hollow-core fibers operating at different spectral regions and conclude the paper with a brief outlook on the future of this potentially transformative technology.

中文翻译：

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空心光纤中的损耗：机制、缩放规则和限制

在过去几年中，空心光纤技术的进步已将这些光纤的衰减降低到与全实心石英芯单模光纤相当的水平。该领域持续的进步步伐重新激发了人们对该技术的兴趣，并产生了这样的期望，即有朝一日它将实现有史以来最透明的光传播波导，涵盖所有感兴趣的光谱区域。在这项工作中，我们回顾并分析了驱动空心光纤衰减的各种物理机制。我们既考虑了有点传统的空心光子带隙技术，也考虑了最近的反共振空心光纤。由于这两种光纤类型利用与传统实心光纤不同的引导机制将光限制在中心纤芯，它们的衰减也受一组不同的物理过程支配，我们在此详细分析。首先，我们讨论完美和理想化光纤中的固有损耗机制。这些包括泄漏损耗、吸收和填充纤芯的气体或周围玻璃微结构的散射，以及纤维内空气-玻璃界面的粗糙度散射。对后者的贡献进行了严格的分析，澄清了文献中经常导致使用不适当的缩放规则的不准确之处。然后，我们探讨了对损失的外在贡献，并讨论了随机微弯的影响以及可能由制造过程中的缺陷导致的其他扰动和不均匀性的影响。这些效应主要通过将光从基模散射到损耗更高的高阶模和包层模中来影响光纤的损耗。尽管这些贡献经常被忽视，但在有朝一日生产损耗低于 0.1 dB/km 和纯单模制导的空心光纤的背景下，它们的作用变得越来越重要。最后，我们提出了前面提到的所有损失机制的一般缩放规则，并将它们结合起来检查最近报告的光纤的性能。我们为在不同光谱区域工作的低损耗空心光纤的设计制定了一些通用指南，并以对这种潜在变革性技术的未来的简要展望作为本文的结尾。尽管这些贡献经常被忽视，但在有朝一日生产损耗低于 0.1 dB/km 和纯单模制导的空心光纤的背景下，它们的作用变得越来越重要。最后，我们提出了前面提到的所有损失机制的一般缩放规则，并将它们结合起来检查最近报告的光纤的性能。我们为在不同光谱区域工作的低损耗空心光纤的设计制定了一些通用指南，并以对这种潜在变革性技术的未来的简要展望作为本文的结尾。尽管这些贡献经常被忽视，但在有朝一日生产损耗低于 0.1 dB/km 和纯单模制导的空心光纤的背景下，它们的作用变得越来越重要。最后，我们提出了前面提到的所有损失机制的一般缩放规则，并将它们结合起来检查最近报告的光纤的性能。我们为在不同光谱区域工作的低损耗空心光纤的设计制定了一些通用指南，并以对这种潜在变革性技术的未来的简要展望作为本文的结尾。我们为前面提到的所有损失机制提供了一般缩放规则，并将它们结合起来检查最近报告的光纤的性能。我们为在不同光谱区域工作的低损耗空心光纤的设计制定了一些通用指南，并以对这种潜在变革性技术的未来的简要展望作为本文的结尾。我们为前面提到的所有损失机制提供了一般缩放规则，并将它们结合起来检查最近报告的光纤的性能。我们为在不同光谱区域工作的低损耗空心光纤的设计制定了一些通用指南，并以对这种潜在变革性技术的未来的简要展望作为本文的结尾。