Topological One-Way Edge States in an Air-Hole Honeycomb Gyromagnetic Photonic Crystal

Abstract

Topological one-way edge states have attracted increasing attention because of their intriguing fundamental physics and potential applications, particularly in the realm of photonics. In this paper, we present a theoretical and numerical demonstration of topological one-way edge states in an air-hole honeycomb gyromagnetic photonic crystal biased by an external magnetic field. Localized horizontally to the edge and confined in vertical direction by two parallel metallic plates, these unique states possess robust one-way propagation characteristics. They are strongly robust against various types of defects, imperfections and sharp corners on the path, and even can unidirectionally transport along the irregular edges of arbitrary geometries. We further utilize the one-way property of edge states to overcome entirely the issue of back-reflections and show the design of topological leaky wave antennas. Our results open a new door towards the observation of nontrivial edge states in air-hole topological photonic crystal systems, and offer useful prototype of robust topological photonic devices, such as geometry-independent topological energy flux loops and topological leaky wave antennas.

Topological photonic states in gyromagnetic photonic crystals: Physics, properties, and applications

“…To further explore the potential applications of TPSs in various topological photonic systems, an amount of functionalities and prototypes of topological photonic devices have been implemented, including but not limited to multimode one-way waveguides, [34,35] high-throughput one-way waveguides, [86,94] topological antennas, [95][96][97] topological one-way delay-lines, [48,88,90,98,99] topological beam splitters, [52,84] topological laser, [47] and topological one-way fiber. [100] In this section, we will mainly give a brief introduction of two typical topological photonic applications in GPCs, topological laser [47] and topological one-way fiber.…”

Topological Resistance-Free One-Way Transport in a Square-Hexagon Lattice Gyromagnetic Photonic Crystal

“…In this scenario, one-way edge states emerge with topological protection properties, allowing photons to propagate in one direction and forbidding backscattering under any type of imperfections. Utilizing this one-way property, one can construct numerous useful photonic devices, such as topological dispersionless slow light states [ 22 , 23 , 24 ], topological splitters [ 6 , 25 ], topological lasers [ 26 ] and topological antennas [ 27 , 28 ]. Contextually, a natural question appears: can PCTIs offer an effective solution to avoid mode-mixing problems and impedance-mismatching issues at terminates, intersections and discontinuities in designing PhCs-based circuits and devices, besides the one-way transport property?…”