We demonstrate how to reduce the loss in photonic bandgap fibers by orders of magnitude by varying the radius of the corner strands in the core surround. As a fundamental working principle we find that changing the corner strand radius can lead to backscattering of light into the fiber core. Selecting an optimal corner strand radius can thus reduce the loss of the fundamental core mode in a specific wavelength range by almost two orders of magnitude when compared to an unmodified cladding structure. Using the optimal corner radius for each transmission window, we observe the low-loss behavior for the first and second bandgaps, with the losses in the second bandgap being even lower than that of the first one. Our approach of reducing the confinement loss is conceptually applicable to all kinds of photonic bandgap fibers including hollow core and all-glass fibers as well as on-chip light cages. Therefore, our concept paves the way to low-loss light guidance in such systems with substantially reduced fabrication complexity.

中文翻译：

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通过设计纤芯环绕结构，可减少光子带隙光纤的数量级损失

我们演示了如何通过改变纤芯周围的角股的半径，将光子带隙光纤的损耗降低几个数量级。作为一项基本的工作原理，我们发现更改角线束半径会导致光反向散射到光纤纤芯中。因此，与未经修改的包层结构相比，选择最佳的角股半径可以在特定波长范围内将基本纤芯模的损耗降低近两个数量级。使用每个传输窗口的最佳拐角半径，我们观察到第一和第二带隙的低损耗行为，第二个带隙的损耗甚至低于第一个带隙的损耗。我们降低限制损耗的方法从概念上讲适用于所有类型的光子带隙光纤，包括中空纤芯和全玻璃光纤以及片上光保持架。因此，我们的构思为在这种系统中实现低损耗的光导铺平了道路，并大大降低了制造复杂性。