Non-diffracting polarization features around far-field zeros of electromagnetic radiation

Alex Vernon, Andrew Kille, Francisco Rodriguez Fortuno*, Andrei Afanasev*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Light from any physical source diffracts over space, as spherical wavefronts grow and energy density is spread out. Diffractive effects pose fundamental limits to light-based technologies, including communications, spectroscopy, and metrology. Polarization becomes paraxial in the far-field limit, and, by ignoring longitudinal field components, the rich physics of non-paraxial fields that exist in near-fields or a beam's tight focus is lost. The longitudinal field cannot, however, be ignored when transverse field components vanish (in a transverse field zero) and carry a small non-paraxial region to infinity.We show that a transverse field zero is always accompanied by non-diffracting polarization structures, whose geometries are independent of the distance to the source, including an enclosing intensity ratio tube, and parallel, non-diverging polarization singularities.We illustrate these features in multipole radiation and in double-slit interference, two examples that have time-fixed transverse field zeros. Non-diffracting structures with a changing position are coupled to time-varying zeros, which are present in all far-field radiation.

Original languageEnglish
Pages (from-to)120-127
Number of pages8
JournalOptica
Volume11
Issue number1
DOIs
Publication statusPublished - 18 Jan 2024

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