Electromagnetic Helicity in Complex Media

Filippo Alpeggiani, K. Y. Bliokh, F. Nori, L. Kuipers

Research output: Contribution to journalArticleScientificpeer-review

54 Citations (Scopus)
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Optical helicity density is usually discussed for monochromatic electromagnetic fields in free space. It plays an important role in the interaction with chiral molecules or nanoparticles. Here we introduce the optical helicity density in a dispersive isotropic medium. Our definition is consistent with biorthogonal Maxwell electromagnetism in optical media and the Brillouin energy density as well as with the recently introduced canonical momentum and spin of light in dispersive media. We consider a number of examples, including electromagnetic waves in dielectrics, negative-index materials, and metals, as well as interactions of light in a medium with chiral and magnetoelectric molecules.
Original languageEnglish
Article number243605
JournalPhysical Review Letters
Issue number24
Publication statusPublished - 2018


  • Electromagnetism
  • Negative Refraction
  • Photonics


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