Topological antennas: Aperture radiators, leaky-wave surfaces, and orbital angular momentum beam generation

The emerging field of topological photonics has extended our capability to control and manipulate electromagnetic waves. Thus far, however, research focused on realizing defect-immune waveguides for on-chip communication. Making similar advancement antennas, which are an integral component crucial the performance wireless devices, could lead a parallel impact In particular, requirement impedance matching that is fundamental current antenna technology constitutes major limitation transmitting receiving free-space signals in terms bandwidth power efficiency. Here, we show how reciprocal photonic insulator (PTI) metasurfaces can be designed enable unique radiation mechanism needless matching. This relies fact counter-propagating spin states decoupled from each other; hence, this self-matching characteristic spans entire PTI’s bandgap. Specifically, present two strategies out-coupling spin-polarized edge modes: (1) form end-fire at abrupt termination PTI with free space (2) leaky-wave by engineering dispersion mode lie above light line. first approach, compare results conventional rectangular waveguide apertures planar Vivaldi either have large profile or flared ends obtain gradual second demonstrate structure emit orbital angular momentum (OAM) beams various charge numbers simply varying length interface when made into circular loop. reduced device area complexity due removing need any network ability easily multiplex OAMs charge, addition wideband high efficiency performance, make proposed antennas highly attractive many applications.