Nonlinear imaging of nanoscale topological corner states

Abstract

Topological states of light represent counterintuitive optical modes localized at boundaries of finite-size optical structures that originate from the properties of the bulk. Being defined by bulk properties, such boundary states are insensitive to certain types of perturbations, thus naturally enhancing robustness of photonic circuitries. Conventionally, the N-dimensional bulk modes correspond to (N-1)-dimensional boundary states. The higher-order bulk-boundary correspondence relates N-dimensional bulk to boundary states with dimensionality reduced by more than 1. A special interest lies in miniaturization of such higher-order topological states to the nanoscale. Here, we realize nanoscale topological corner states in metasurfaces with C6-symmetric honeycomb lattices. We directly observe nanoscale topology-empowered edge and corner localizations of light and enhancement of light-matter interactions via a nonlinear imaging technique. Control of light at the nanoscale empowered by topology may facilitate miniaturization and on-chip integration of classical and quantum photonic devices.

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• Topologically protected second-harmonic generation via doubly resonant high-order photonic modes
• An operator-based approach to topological photonics
• Local markers for crystalline topology
• Nonlinear photonic disclination states
• Spin-Polarized Fractional Corner Charges and Their Photonic Realization
• Vortex solitons in topological disclination lattices
• Tutorial: Classifying Photonic Topology Using the Spectral Localizer and Numerical $K$-Theory
• Observation of nonlinearity-controlled switching of topological edge states
• Nonlinear dielectric geometric-phase metasurface with simultaneous structure and lattice symmetry design
• Light bullets in Su-Schrieffer-Heeger photonic topological insulators
• Observation of gapless corner modes in synthetic translation dimensions
• Polarization-independent second-order photonic topological corner states
• Topological gap solitons in Rabi Su-Schrieffer-Heeger lattices
• Observation of nonlinear higher-order topological insulators with unconventional boundary truncations
• Quadratic solitons in higher-order topological insulators
• Topological Photonics on a Small Scale
• Nanoimprinted topological laser in the visible