Internal fields of a spherical particle illuminated by a tightly focused laser beam: Focal point positioning effects at resonance

J. P. Barton, D. R. Alexander, S. A. Schaub

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Abstract

The spherical particle/arbitrary beam interaction theory developed in an earlier paper is used to investigate the dependence of structural resonance behavior on focal point positioning for a spherical particle illuminated by a tightly focused (beam diameter less than sphere diameter), linearly polarized, Gaussian-profiled laser beam. Calculations of absorption efficiency and distributions of normalized source function (electric field magnitude) are presented as a function of focal point positioning for a particle with a complex relative index of refraction of n̄=1.33+5.0×10- 6i and a size parameter of α≊29.5 at both nonresonance and resonance conditions. The results of the calculations indicate that structural resonances are not excited during the on-center focal point positioning of such a tightly focused beam but structural resonances can be excited by proper on-edge focal point positioning. Electric wave resonances were found to be excited by moving the focal point from on-center towards the edge of the sphere parallel to the direction of the incident beam electric field polarization. Magnetic wave resonances were found to be excited by moving the focal point from on-center towards the edge of the sphere perpendicular to the direction of the incident beam electric field polarization.

Original languageEnglish (US)
Pages (from-to)2900-2906
Number of pages7
JournalJournal of Applied Physics
Volume65
Issue number8
DOIs
StatePublished - Dec 1 1989

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ASJC Scopus subject areas

  • Physics and Astronomy(all)

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