Understanding the impact of the cladding tube structure on the overall guiding performance is crucial for designing a single-mode, wide-band, and ultra low-loss nested hollow-core anti-resonant fiber (HC-ARF). Here we thoroughly investigate on how the propagation loss is affected by the nested elements when their geometry is realistic (i.e., non-ideal). Interestingly, it was found that the size, rather than the shape, of the nested elements has a dominant role in the final loss performance of the regular nested HC-ARFs. We identify a unique ‘V-shape’ pattern for suppression of higher-order modes loss by optimizing free design parameters of the HC-ARF. We find that a 5-tube nested HC-ARF has wider transmission window and better single-mode operation than a 6-tube HC-ARF. We show that the propagation loss can be significantly improved by using anisotropic nested anti-resonant tubes elongated in the radial direction. Our simulations indicate that with this novel fiber design, a propagation loss as low as 0.11 dB/km at 1.55 μm can be achieved. Our results provide design insight toward fully exploiting a single-mode, wide-band, and ultra low-loss HC-ARF. In addition, the extraordinary optical properties of the proposed fiber can be beneficial for several applications such as future optical communication system, high energy light transport, extreme non-nonlinear optics and beyond.

中文翻译：

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包层元素对空心抗谐振纤维损耗性能的影响

了解包层管结构对整体导引性能的影响对于设计单模，宽带和超低损耗的嵌套空心空心反谐振光纤（HC-ARF）至关重要。在这里，我们彻底研究了嵌套元素的几何形状是现实的（例如，不理想）。有趣的是，发现嵌套元素的大小而不是形状在常规嵌套HC-ARF的最终损耗性能中起主导作用。我们通过优化HC-ARF的自由设计参数，确定了一种独特的“ V形”图案来抑制高阶模损耗。我们发现，与6管HC-ARF相比，5管嵌套HC-ARF具有更宽的传输窗口和更好的单模运行。我们表明，通过使用在径向方向上伸长的各向异性嵌套反谐振管，可以显着改善传播损耗。我们的模拟表明，用这种新颖的光纤设计中，传播损耗低至0.11分贝/千米，在1.55 μm可以实现。我们的结果为全面开发单模，宽带和超低损耗HC-ARF提供了设计见解。另外，所提出的光纤的非凡的光学特性对于诸如未来的光通信系统，高能光传输，极端的非线性光学器件等等的一些应用可能是有益的。