Type-II Dirac photons at the metasurfaces
Abstract
Topological characteristics of energy bands, such as Dirac/Weyl nodes, have attracted substantial interest in condensed matter systems as well as in classical wave systems. Among these energy bands, the type-II Dirac point is a nodal degeneracy with tilted conical dispersion, leading to a peculiar crossing dispersion in the constant energy plane. Such nodal points have recently been found in electronic materials. The analogous topological feature in photonic systems remains a theoretical curiosity, with experimental realization expected to be challenging. Here, we experimentally realize the type-II Dirac point using a planar metasurface architecture, where the band degeneracy point is protected by the underlying mirror symmetry of the metasurface. Gapless edge modes are found and measured at the boundary between the different domains of the symmetry-broken metasurface. Our work shows that metasurfaces are simple and practical platforms for realizing electromagnetic type-II Dirac points, and their planar structure is a distinct advantage that facilitates applications in two-dimensional topological photonics.
Cite
@article{arxiv.1803.08743,
title = {Type-II Dirac photons at the metasurfaces},
author = {Chuandeng Hu and Zhenyu Li and Rui Tong and Xiaoxiao Wu and Zengzilu Xia and Li Wang and Shanshan Li and Yingzhou Huang and Shuxia Wang and Bo Hou and C. T. Chan and Weijia Wen},
journal= {arXiv preprint arXiv:1803.08743},
year = {2018}
}