Evolution of topological edge modes from honeycomb photonic crystals to triangular-lattice photonic crystals

Abstract

The presence of topological edge modes at the interface of two perturbed honeycomb photonic crystals with $C_6$ symmetry is often attributed to the different signs of Berry curvature at the K and K${}^{\prime }$ valleys. In contrast to the electronic counterpart, the Chern number defined in photonic valley Hall effect is not a quantized quantity but can be tuned to finite values including zero simply by changing geometrical perturbations. Here, we argue that the edge modes in photonic valley Hall effect can exist even when Berry curvature vanishes. We numerically demonstrate the presence of the zero-Berry-curvature edge modes in triangular lattice photonic crystal slab structures in which $C_3$ symmetry is maintained but inversion symmetry is broken. We investigate the evolution of the Berry curvature from the honeycomb-lattice photonic crystal slab to the triangular-lattice photonic crystal slab and show that the triangular-lattice photonic crystals still support edge modes in a very wide photonic bandgap. Additionally, we find that the edge modes with zero Berry curvature can propagate with extremely low bending loss.

arXiv comment8 pages, 10 figures including supplementary information

References in corpus (20)

• Topological Insulators
• Quantum Spin Hall Effect in Graphene
• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Photonic Floquet Topological Insulators
• Possible Realization of Directional Optical Waveguides in Photonic Crystals with Broken Time-Reversal Symmetry
• Photonic Analogue of Two-dimensional Topological Insulators and Helical One-Way Edge Transport in Bi-Anisotropic Metamaterials
• Scheme to Achieve Silicon Topological Photonics
• Reflection-Free One-Way Edge Modes in a Gyromagnetic Photonic Crystal
• All-Si Valley-Hall Photonic Topological Insulator
• Deterministic photon-emitter coupling in chiral photonic circuits
• A Silicon-on-Insulator Slab for Topological Valley Transport
• Experimental realization of photonic topological insulator in a uniaxial metacrystal waveguide
• Visualization of unidirectional optical waveguide using topological photonic crystals made of dielectric material
• Novel Topological Phase with Zero Berry Curvature
• Valley-contrasting orbital angular momentum in photonic valley crystals
• Valley-protected backscattering suppression in silicon photonic graphene
• Chiral topological photonics with an embedded quantum emitter
• On the robustness of topological corner modes in photonic crystals
• Gapless Unidirectional Photonic Transport Using All-Dielectric Kagome Lattices
• The Nature of Topological Protection in Spin and Valley Hall Insulators

Cited by in corpus (7)

• On-chip unidirectional waveguiding for surface acoustic waves along a defect line in a triangular lattice
• High Transmission in 120-degree Sharp Bends of Inversion-symmetric and Inversion-asymmetric Photonic Crystal Waveguides
• Topologically Protected Edge States in Triangular Lattices
• Experimental probe of band structures of bilayer valley photonic crystals
• Design of a room-temperature topological exciton-polariton laser in a ZnO/TiO${}_2$-photonic crystal slab
• Topological Pseudospin Hall Effect and Multi-frequency Corner Modes in Kagome-based Lattices
• Fine Structures of Berry Curvature and Unquantized Valley Chern Numbers in Valley Photonic Crystals