Weyl points and line nodes in gapless gyroid photonic crystals

TL;DR

This paper reports the discovery of Weyl points and line nodes in double-gyroid photonic crystals, demonstrating topologically non-trivial surface states and flat bands, with potential for experimental realization at various frequencies.

Contribution

It presents the first realization of Weyl points in photonic crystals based on double-gyroid structures, including detailed phase diagrams and surface state analysis.

Findings

Weyl points are frequency-isolated and topologically non-trivial.

Surface states associated with Weyl points are demonstrated.

Line nodes with flat band surface states are identified.

Abstract

Weyl points and line nodes are three-dimensional linear point- and line-degeneracies between two bands. In contrast to Dirac points, which are their two-dimensional analogues, Weyl points are stable in the momentum space and the associated surface states are predicted to be topologically non-trivial. However, Weyl points are yet to be discovered in nature. Here, we report photonic crystals, based on the double-gyroid structures, exhibiting frequency-isolated Weyl points with intricate phase diagrams. The surface states associated with the non-zero Chern numbers are demonstrated. Line nodes are also found in similar geometries; the associated surface states are shown to be flat bands. Our results are readily experimentally realizable at both microwave and optical frequencies.