Type-II Dirac photons at the metasurfaces

Abstract

Topological characteristics of energy bands, such as Dirac/Weyl nodes, have attracted substantial interest in condensed matter systems as well as in classical wave systems. Among these energy bands, the type-II Dirac point is a nodal degeneracy with tilted conical dispersion, leading to a peculiar crossing dispersion in the constant energy plane. Such nodal points have recently been found in electronic materials. The analogous topological feature in photonic systems remains a theoretical curiosity, with experimental realization expected to be challenging. Here, we experimentally realize the type-II Dirac point using a planar metasurface architecture, where the band degeneracy point is protected by the underlying mirror symmetry of the metasurface. Gapless edge modes are found and measured at the boundary between the different domains of the symmetry-broken metasurface. Our work shows that metasurfaces are simple and practical platforms for realizing electromagnetic type-II Dirac points, and their planar structure is a distinct advantage that facilitates applications in two-dimensional topological photonics.

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Cited by in corpus (10)

• Hyperbolic Metamaterials: From Dispersion Manipulation to Application
• Tilted and type-III Dirac cones emerging from flat bands in photonic orbital graphene
• Nonlinear Topological Valley Hall Edge States Arising from Type-II Dirac Cones
• Topologically protected Fano resonance in photonic valley Hall insulators
• Deterministic scheme for two-dimensional type-II Dirac points and experimental realization in acoustics
• Quantum electrodynamics in anisotropic and tilted Dirac photonic lattices
• Type-II Dirac photonic lattices
• Topological modes in radiofrequency resonator arrays
• Topological Degeneracy Induced by Twisting
• $\mathcal{P}\mathcal{T}$-symmetric photonic lattices with type-II Dirac cones