Ideal Nodal Rings of One-Dimensional Photonic Crystals in the Visible Region

TL;DR

This paper demonstrates the theoretical design and experimental realization of an ideal nodal ring in the visible spectrum using a simple one-dimensional photonic crystal, enabling exploration of 3D topological physics in nanophotonics.

Contribution

It introduces a straightforward 1D photonic crystal platform for realizing 3D topological states, simplifying previous complex designs and enabling nanoscale applications.

Findings

Realized an ideal nodal ring in the visible spectrum

Demonstrated pi Berry phase via reflection phase winding

Gapped the nodal ring to produce photonic ridge states

Abstract

Three-dimensional (3D) artificial metacrystals host rich topological phases, such as Weyl points, nodal rings and 3D photonic topological insulators. These topological states enable a wide range of applications, including 3D robust waveguide, one-way fiber and negative refraction of surface wave. However, these carefully designed metacrystals are usually very complex, hindering their extension to nanoscale photonic systems. Here, we theoretically proposed and experimentally realized an ideal nodal ring in visible region using a simple 1D photonic crystal. The pi Berry phase around the ring is manifested by a 2pi reflection phase's winding and the resultant drumhead surface states. By breaking the inversion symmetry, the nodal ring can be gapped and the pi-Berry phase would diffuse into a toroidal shaped Berry flux, resulting in photonic ridge states (the 3D extension of quantum valley Hall states). Our results provide a simple and feasible platform for exploring 3D topological physics and their potential applications in nanophotonics.