Momentum paradox in a vortex core

R Zambrini, L C Thomson, S M Barnett, M Padgett

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


The identification of angular momentum l (h) over bar per photon with optical vortices of charge l appears to require that the field amplitude be zero within a finite distance of the vortex. This, however, is not compatible with the known form of beams such as the Laguerre - Gaussian and Bessel beams. We resolve this paradox by analysing the propagation of a Bessel beam through a small circular aperture, showing that the resulting field has evanescent components.

Original languageEnglish
Pages (from-to)1135-1144
Number of pages10
JournalJournal of Modern Optics
Issue number8
Publication statusPublished - 20 May 2005


  • orbital angular-momentum
  • gaussian layer modes
  • electromagnetic fields
  • scalar representation
  • poynting vector
  • light
  • density


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