Visualization of higher-order topological insulating phases in two-dimensional dielectric photonic crystals

Abstract

The studies of topological phases of matter have been extended from condensed matter physics to photonic systems, resulting in fascinating designs of robust photonic devices. Recently, higher-order topological insulators (HOTIs) have been investigated as a novel topological phase of matter beyond the conventional bulk-boundary correspondence. Previous studies of HOTIs have been mainly focused on the topological multipole systems with negative coupling between lattice sites. Here we experimentally demonstrate that second-order topological insulating phases without negative coupling can be realized in two-dimensional dielectric photonic crystals (PCs). We visualize both one-dimensional topological edge states and zero-dimensional topological corner states by using near-field scanning technique. To characterize the topological properties of PCs, we define a novel topological invariant based on the bulk polarizations. Our findings open new research frontiers for searching HOTIs in dielectric PCs and provide a new mechanism for light-manipulating in a hierarchical way.

23 pages, 4 figures

References in corpus (12)

• Topological Photonics
• Photonic Analogue of Two-dimensional Topological Insulators and Helical One-Way Edge Transport in Bi-Anisotropic Metamaterials
• Scheme to Achieve Silicon Topological Photonics
• Electric Multipole Moments, Topological Multipole Moment Pumping, and Chiral Hinge States in Crystalline Insulators
• Topological Acoustics
• $(d-2)$-dimensional edge states of rotation symmetry protected topological states
• Reflection symmetric second-order topological insulators and superconductors
• Higher-order topological insulators and semimetals on the breathing Kagome and pyrochlore lattices
• Direct observation of corner states in second-order topological photonic crystal slabs
• Selective enhancement of topologically induced interface states in a dielectric resonator chain
• Novel Topological Phase with Zero Berry Curvature
• Quantum interference of topological states of light

Cited by in corpus (12)

• Direct observation of corner states in second-order topological photonic crystal slabs
• Active topological photonics
• Realization of an acoustic third-order topological insulator
• Higher-Order Weyl Semimetals
• Topolectrical-circuit octupole insulator with topologically protected corner states
• Topological Semimetal Nanostructures: From Properties to Topotronics
• Cavity Quantum Electrodynamics with Second-Order Topological Corner State
• Plasmon-polaritonic quadrupole topological insulators
• Nonlinear higher-order polariton topological insulator
• Simulation of topological phases with color center arrays in phononic crystals
• Direct visualization of topological transitions and higher-order topological states in photonic metasurfaces
• Higher-order Quantum Spin Hall Effect of Light