The success of photonic crystal fibres relies largely on the endless variety of two-dimensional photonic crystals in the cross-section. Here, we propose a topological bandgap fibre whose bandgaps along in-plane directions are opened by generalised Kekulé modulation of a Dirac lattice with a vortex phase. Then, the existence of mid-gap defect modes is guaranteed to guide light at the core of this Dirac-vortex fibre, where the number of guiding modes equals the winding number of the spatial vortex. The single-vortex design provides a single-polarisation single-mode for a bandwidth as large as one octave.

中文翻译：

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Dirac-涡旋拓扑光子晶体光纤

光子晶体光纤的成功很大程度上取决于截面中无穷无尽的二维光子晶体。在这里，我们提出一种拓扑带隙光纤，其沿面内方向的带隙通过具有涡旋相位的狄拉克晶格的广义Kekulé调制而打开。然后，确保存在中间间隙缺陷模式以在该狄拉克涡旋光纤的核心处引导光，其中，引导模式的数量等于空间涡旋的缠绕数量。单涡旋设计提供了一个单极化单模，带宽高达一个八度。