Topological Vortex and Antivortex Transport in a Three-Dimensional Photonic Disclination Metamaterial

Vortex or antivortex modes that carry orbital angular momentum (OAM) have provided a novel degree of freedom for modern optics and practical applications. However, their robust transport has thus far been limited to two-dimensional photonic systems. Here, we report on the first experimental observation of topological vortex and antivortex transport in a three-dimensional (3D) photonic metamaterial with a topological disclination defect. Using microwave near-field measurements, we directly observe topological vortex and antivortex modes bound to and propagated stably along a one-dimensional disclination line defect with preserved OAM in a 3D photonic disclination metamaterial. Moreover, we demonstrate that topological vortices and antivortices, which transport opposite OAMs, can be selectively excited with chiral sources and are robust against metallic obstacles and random disorders. Our Letter not only establishes an ideal platform for exploring topological lattice defects in 3D photonic systems but also opens a new avenue for designing OAM-based photonic devices.