Experimental realization of a Weyl exceptional ring

Alexander Cerjan, Sheng Huang, Mohan Wang, Kevin P. Chen, Yidong Chong, Mikael C. Rechtsman

Research output: Contribution to journalArticlepeer-review

237 Scopus citations


Weyl points are isolated degeneracies in reciprocal space that are monopoles of the Berry curvature. This topological charge makes them inherently robust to Hermitian perturbations of the system. However, non-Hermitian effects, usually inaccessible in condensed-matter systems, are an important feature of photonic systems, and when added to an otherwise Hermitian Weyl material have been predicted to spread the Berry charge of the Weyl point out onto a ring of exceptional points, creating a Weyl exceptional ring and fundamentally altering its properties. Here, we observe the implications of the Weyl exceptional ring using real-space measurements of an evanescently coupled bipartite optical waveguide array by probing its effects on the Fermi arc surface states and bulk diffraction properties of the two constituent sublattices in an experimental realization of a distributed Berry charge in a topological material.

Original languageEnglish (US)
Pages (from-to)623-628
Number of pages6
JournalNature Photonics
Issue number9
StatePublished - Sep 1 2019

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics


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