Experimental observation of photonic nodal line degeneracies in metacrystals

Research output: Contribution to journalArticlepeer-review

Authors

  • Biao Yang
  • Ben Tremain
  • Qinghua Guo
  • Lingbo Xia
  • Alastair P. Hibbins

Colleges, School and Institutes

Abstract

Nodal line semimetals (NLS) are three-dimensional (3D) crystals that support band crossings in the form of one-dimensional rings in the Brillouin zone. In the presence of spin–orbit coupling or lowered crystal symmetry, NLS may transform into Dirac semimetals, Weyl semimetals, or 3D topological insulators. In the photonics context, despite the realization of topological phases, such as Chern insulators, topological insulators, Weyl, and Dirac degeneracies, no experimental demonstration of photonic nodal lines (NLs) has been reported so far. Here, we experimentally demonstrate NL degeneracies in microwave cut-wire metacrystals with engineered negative bulk plasma dispersion. Both the bulk and surface states of the NL metamaterial are observed through spatial Fourier transformations of the scanned near-field distributions. Furthermore, we theoretically show that the NL degeneracy can transform into two Weyl points when gyroelectric materials are incorporated into the metacrystal design. Our findings may inspire further advances in topological photonics.

Details

Original languageEnglish
Article number950
JournalNature Communications
Volume9
Publication statusPublished - 5 Mar 2018

Keywords

  • metamaterials , sub-wavelength optics