Topologically-Protected One-Way Leaky Waves

We investigate the application of the concept of photonic topological insulators (PTIs)in radiating and scattering structures. The general properties of topologically-protected unidirectional leaky modes are analyzed for a stratified structure composed of a magnetically-biased plasma (a continuum model of topological materials)covered by topologically-trivial materials. We discuss how the propagation and radiation properties of these modes can be controlled by introducing a suitably designed coating layer on the biased plasma, resulting in highly-directive one-way leaky-wave radiation. The topological robustness of these leaky surface waves allows overcoming large defects, corners, and bends along the propagation path without any back-scattering and backward radiation. Our findings may be useful for future leaky-wave (nano)antenna generations and stealth technology based on topological concepts.