Dirac-vortex topological photonic crystal fibre

TL;DR

This paper introduces a topological photonic crystal fibre with a vortex phase that guides light using mid-gap defect modes, offering a large bandwidth and single-polarization single-mode operation based on a Dirac lattice with Kekulé modulation.

Contribution

It presents a novel topological fibre design utilizing a Dirac lattice with vortex phase to achieve robust light guidance with large bandwidth.

Findings

Guides light at the core via mid-gap defect modes.

Supports a single-polarization single mode over an octave bandwidth.

Uses Kekulé modulation of a Dirac lattice with vortex phase.

Abstract

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 generalized Kekul\'e 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-polarization single mode for a bandwidth as large as one octave.