Copropagating Photonic Fermi Arc Channels for Multiplexing and Dynamically Routing Topological Surface Waves

Abstract

Recently, 3D photonic Weyl degeneracies have been realized in both magnetized plasma (MP) and chiral hyperbolic metamaterials (CHM). Both systems can achieve backscattering-immune transportation of light across sharp corners of translation-invariant prisms and they also show similar equal-frequency surfaces (EFSs). Despite this resemblance, their topological properties show striking differences as the Weyl points in MP and CHM arise from broken time-reversal and spatial-inversion symmetries, respectively. Here, using the effective medium approach, an interface formed between an MP and a CHM is investigated, which supports two Fermi arc surface states with nearly identical propagation directions. This leads to novel 3D interface configurations for guiding non-reciprocal surface waves, information multiplexing, and magnetically controllable routing of the signal. This work may find applications in unidirectional excitation and controllable transportation in photonics.