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

Zhihao Lan, Menglin L.N. Chen, Jian Wei You, Wei E.I. Sha

Research output: Journal article publicationJournal articleAcademic researchpeer-review

8 Citations (Scopus)


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 a Dirac cone sandwiched between two domains of photonic crystals with opposite topological properties. In this Letter, we show that an alternative kind of large-area topological waveguide state could be created employing the photonic analogs of the 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 a 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 related to the size of the band gap 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 the robustness of these large-area waveguide modes against sharp bends are explicitly demonstrated. Our work broadens the photonic systems and platforms that could be utilized for large-area-mode-enabled topological waveguiding.

Original languageEnglish
Article numberL041501
JournalPhysical Review A
Issue number4
Publication statusPublished - Apr 2023

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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