Z_2 Photonic topological insulators in the visible wavelength range for robust nanoscale photonics

Abstract

Topological photonics provides an ideal platform for demonstrating novel band topology concepts, which are also promising for robust waveguiding, communication and computation applications. However, many challenges such as extremely large device footprint and functionality at short wavelengths remain to be solved which are required to make practical and useful devices that can also couple to electronic excitations in many important organic and inorganic semiconductors. In this letter, we report an experimental realization of Z_2 photonic topological insulators with their topological edge state energies spanning across the visible wavelength range including in the sub-500 nm regime. The photonic structures are based on deformed hexagonal lattices with preserved six-fold rotational symmetry patterned on suspended SiNx membranes. The experimentally measured energy-momentum dispersion of the topological lattices directly show topological band inversion by the swapping of the brightness of the bulk energy bands, and also the helical edge states when the measurement is taken near the topological interface. The robust topological transport of the helical edge modes in real space is demonstrated by successfully guiding circularly polarized light beams unidirectionally through sharp kinks without major signal loss. This work paves the way for small footprint photonic topological devices working in the short wavelength range that can also be utilized to couple to excitons for unconventional light-matter interactions at the nanoscale.

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Cited by in corpus (13)

• Dirac-vortex topological cavity
• A brief review of topological photonics in one, two, and three dimensions
• On the robustness of topological corner modes in photonic crystals
• Metasurface Integrated Monolayer Exciton Polariton
• Coexistence of pseudospin- and valley-Hall-like edge states in a photonic crystal with $C_{3v}$ symmetry
• A topological photonic ring-resonator for on-chip channel filters
• Berry bands and pseudo-spin of topological photonic phases
• Absence of topological protection of the interface states in ${\mathbb{Z}}_2$ photonic crystals
• Topological valley crystals in a photonic Su-Schrieffer-Heeger (SSH) variant
• Near- and Far-Field Excitation of Topological Plasmonic Metasurfaces
• Realization of Z${}_2$ topological photonic insulators made from multilayer transition metal dichalcogenides
• Spin-dependent gain and loss in photonic quantum spin Hall systems
• Visualization of Photonic Band Structures via Far-field Measurements in SiNx Photonic Crystal Slabs