Dirac-vortex topological photonic crystal fiber

The emergence of topological photonics has revolutionized the paradigm of photonic device design, with its core principle being the utilization of topological invariants to achieve robust control over light propagation and localization. In recent years, this concept has been successfully introduced into fiber optics, giving rise to topological photonic crystal fibers (TPCFs). The Dirac-vortex TPCFs, based on the Jackiw-Rossi zero mode, are realized by introducing a generalized Kekulé modulation in their cross section. This approach exhibits remarkable properties, including a controllable number of modes, a large bandwidth for single-polarization single-mode operation, and robustness against structural disorder. In this paper, we give a comprehensive overview of recent advances in Dirac-vortex TPCFs, including the physical mechanisms with its origin of topological photonic crystals and photonic crystal fibers, theoretical design, and experimental realization. We also discuss opportunities and challenges of Dirac-vortex TPCFs for future applications.