2017/09/10 by Hengyun Zhou, Chao Peng, Yoseob Yoon +6 · 3 citations
Physics and Astronomy · #physics.optics #cond-mat.mes-hall
paper · pdf · doi:10.1126/science.aap9859
published as Science 359, 1009-1012 (2018) · 7 pages, 4 figures
arxiv created 2017/09/10 · arxiv updated 2019/07/09
The ideas of topology have found tremendous success in Hermitian physical systems, but even richer properties exist in the more general non-Hermitian framework. Here, we theoretically propose and experimentally demonstrate a new topologically-protected bulk Fermi arc which---unlike the well-known surface Fermi arcs arising from Weyl points in Hermitian systems---develops from non-Hermitian radiative losses in photonic crystal slabs. Moreover, we discover half-integer topological charges in the polarization of far-field radiation around the Fermi arc. We show that both phenomena are direct consequences of the non-Hermitian topological properties of exceptional points, where resonances coincide in their frequencies and linewidths. Our work connects the fields of topological photonics, non-Hermitian physics and singular optics, and paves the way for future exploration of non-Hermitian topological systems.