Dirac-vortex topological photonic crystal fibre

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. Photonic crystals: Designing novel optical fibers with topological control Numerical calculations reveal how optical fibers composed of topological photonic crystals could allow improved versatility and control over the modes and polarizations of the light they transmit. Photonic crystals have compositions that create “bandgaps” preventing the passage of light with waves of specific energies and momenta. Hao Lin and Ling Lu at the Institute of Physics of the Chinese Academy of Sciences, base their novel method to transmit pure “single mode” light, over a large frequency range, using a topological feature known as a “Dirac-vortex”. In principle, it could lead to applications that can transmit light signals more stably over long distances. At present, the work is theoretical, but the authors suggest that the fibers could be made from silica using existing stack-and-draw or 3-D printing technologies. Fabrication and testing are the next desirable steps.