Broadband Topological Edge-States in Two-Dimensional Terahertz Photonic Crystals with Metallic Elliptical Cylinders

Abstract

originating from the discovery of the quantum spin Hall effect (QSHE), the topological edge states (TES) have been a novel way to control the electromagnetic propagation. According to the time-spatial reversal symmetry and topological defect theory, we propose a topological photonic crystal (TPC) made of elliptical cylinders in the terahertz regime, which possesses a large operation bandwidth. Multiple topological transitions between the trivial and topological structures can be realized by breaking the spatial reversal symmetry instead of breaking the time reversal symmetry. The interfaces between the trivial and nontrivial areas can produce one-way propagating edge states that propagate around sharp corners without backscattering. Our finding provides a platform for the development of TPC-based devices and open up unprecedented venues for topological signal processing and sensing.