Large-area quantum-spin-Hall waveguide states in a three-layer topological photonic crystal heterostructure

Abstract

Topological photonic edge states are conventionally formed at the interface between two domains of topologically trivial and nontrivial photonic crystals. Recent works exploiting photonic quantum Hall and quantum valley Hall effects have shown that large-area topological waveguide states could be created in a three-layer topological heterostructure that consists of a finite-width domain featuring Dirac cone sandwiched between two domains of photonic crystals with opposite topological properties. In this work, we show that a new kind of large-area topological waveguide states could be created employing the photonic analogs of quantum spin Hall effect. Taking the well-used Wu-Hu model in topological photonics as an example, we show that sandwiching a finite-width domain of photonic crystals featuring double Dirac cone between two domains of expanded and shrunken unit cells could lead to the emergence of large-area topological helical waveguide states distributed uniformly in the middle domain. Importantly, we unveil a power-law scaling regarding to the size of the bandgap within which the large-area helical states reside as a function of the width of the middle domain, which implies that these large-area modes in principle could exist in the middle domain with arbitrary width. Moreover, pseudospin-momentum locking unidirectional propagations and robustness of these large-area waveguide modes against sharp bends are explicitly demonstrated. Our work enlarges the photonic systems and platforms that could be utilized for large-area-mode enabled topologically waveguiding.

close to published version

References in corpus (10)

• Topological Photonics
• Photonic Analogue of Two-dimensional Topological Insulators and Helical One-Way Edge Transport in Bi-Anisotropic Metamaterials
• Scheme to Achieve Silicon Topological Photonics
• Analogs of quantum Hall effect edge states in photonic crystals
• Classical higher-order topological insulators
• Topological one-way large-area waveguide states in magnetic photonic crystals
• A brief review of topological photonics in one, two, and three dimensions
• Second-harmonic generation via double topological valley-Hall kink modes in all-dielectric photonic crystals
• Coexistence of pseudospin- and valley-Hall-like edge states in a photonic crystal with $C_{3v}$ symmetry
• Comparative study of Hermitian and non-Hermitian topological dielectric photonic crystals

Cited by in corpus (2)

• Band alignment effect in the topological photonic alloy
• Extraction of power transmission parameters from PT-symmetric waveguides