Higher-order topological phases in tunable $C_3$-symmetric photonic crystals

Abstract

We demonstrate that multiple higher-order topological transitions can be triggered via the continuous change of the geometry in kagome photonic crystals composed of three dielectric rods. By tuning a single geometry parameter, the photonic corner and edge states emerge or disappear with the higher-order topological transitions. Two distinct higher-order topological insulator phases and a normal insulator phase are revealed. Their topological indices are obtained from symmetry representations. A photonic analog of fractional corner charge is introduced to distinguish the two higher-order topological insulator phases. Our predictions can be readily realized and verified in configurable dielectric photonic crystals.

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• On-chip unidirectional waveguiding for surface acoustic waves along a defect line in a triangular lattice
• Topological properties of two-dimensional photonic square lattice without $C_4$ and $M_{x(y)}$ symmetries
• High-Order Topological Phase Diagram Revealed by Anomalous Nernst Effect in Janus ScClI Monolayer
• Dirac cones and higher-order topology in quasi-continuous media
• Topological light guiding and trapping via shifted photonic crystal interfaces
• Observation of gapless corner modes in synthetic translation dimensions
• Observation of topologically distinct corner states in "bearded" photonic Kagome lattices
• Effective action approach to the filling anomaly in crystalline topological matter
• Observation of Dual-band Topological Corner Modes in Acoustic Kagome Lattice with Long-range Interactions
• Ferroelectric polarization controlled orbital Hall conductivity in a higher-order topological insulator: \textit{d1T}-phase monolayer MoS${}_2$
• Observation of nonlinear higher-order topological insulators with unconventional boundary truncations
• Topological Corner States in Bilayer and Trilayer Systems with Vertically Stacked Topological Heterostructures
• Quadratic solitons in higher-order topological insulators
• Manipulation of photonic topological edge and corner states via trivial claddings