Arbitrary-Charged Weyl Points in One-Dimensional Helical Photonic Crystals

Abstract

The exotic physical properties of the Weyl points are mainly determined by their topological charges. Protected by crystallographic symmetries, Weyl charges on highly symmetric points can be larger than 1, termed multiple Weyl points. However, for all types of 3D crystals with 230 space groups, the orders of (screw) rotation axes can only be 1, 2, 3, 4, or 6, limiting the maximal Weyl charge of a natural 3D material to be 4. Here, we demonstrate that arbitrary-charged Weyl points can be stabilized in a 1D helical photonic crystal. Moreover, we give a complete theoretical analysis of all types of 1D HPCs and multiple Weyl points therein. Our findings offer a generally applicable strategy for designing arbitrary-ordered axes and realizing arbitrary-charged Weyl points in classical wave systems.