Topological edge states in photonic Floquet insulator with unpaired Dirac cones

Abstract

Topological insulators are most frequently constructed using lattices with specific degeneracies in their linear spectra, such as Dirac points. For a broad class of lattices, such as honeycomb ones, these points and associated Dirac cones generally appear in non-equivalent pairs. Simultaneous breakup of the time-reversal and inversion symmetry in systems based on such lattices may result in the formation of the unpaired Dirac cones in bulk spectrum, but the existence of topologically protected edge states in such structures remains an open problem. Here photonic Floquet insulator on honeycomb lattice with unpaired Dirac cones in its spectrum is introduced that can support unidirectional edge states appearing at the edge between two regions with opposite sublattice detuning. Topological properties of this system are characterized by the nonzero valley Chern number. Remarkably, edge states in this system can circumvent sharp corners without inter-valley scattering even though there is no total forbidden gap in the spectrum. Our results reveal unusual interplay between two different physical mechanisms of creation of topological edge states based on simultaneous breakup of different symmetries of the system.

9 pages, 7 figures. To appear in Photonics Research. Comments are welcome

References in corpus (25)

• The electronic properties of graphene
• Topological Photonics
• Analogs of quantum Hall effect edge states in photonic crystals
• Classical higher-order topological insulators
• Photonic Topological Anderson Insulators
• Polariton $\mathbb{Z}$ Topological Insulator
• Nonlinear second-order photonic topological insulators
• Light control with Weyl semimetals
• Unveiling pseudospin and angular momentum in photonic graphene
• Observation of strong backscattering in valley-Hall photonic topological interface modes
• Hybrid topological photonic crystals
• Tight-binding methods for general longitudinally driven photonic lattices -- edge states and solitons
• Vector Topological Edge Solitons in Floquet Insulators
• Edge Solitons in Lieb Topological Floquet Insulators
• Observation of nonlinear disclination states
• Topological dipole Floquet solitons
• Observation of $\pi$ solitons in oscillating waveguide arrays
• Bragg solitons in topological Floquet insulators
• Dark topological valley Hall edge solitons
• Interface states in polariton topological insulators
• Visual observation of optical Floquet-Bloch oscillations
• Valley Hall edge solitons in a photonic graphene
• Vector valley Hall edge solitons in superhoneycomb lattices
• Floquet edge solitons in modulated trimer waveguide arrays
• Floquet topological insulators with hybrid edges