Degree of polarization for optical near fields

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© 2002 American Physical Society (APS). http://www.aps.org/

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Volume Title

School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2002

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Mcode

Degree programme

Language

en

Pages

016615

Series

Physical Review E, Volume 66, Issue 1

Abstract

We investigate an extension to the concept of degree of polarization that applies to arbitrary electromagnetic fields, i.e., fields whose wave fronts are not necessarily planar. The approach makes use of generalized spectral Stokes parameters that appear as coefficients, when the full 3×3 spectral coherence matrix is expanded in terms of the Gell-Mann matrices. By defining the degree of polarization in terms of these parameters in a manner analogous to the conventional planar-field case, we are led to a formula that consists of scalar invariants of the spectral coherence matrix only. We show that attractive physical insight is gained by expressing the three-dimensional degree of polarization explicitly with the help of the correlations between the three orthogonal spectral components of the electric field. Furthermore, we discuss the fundamental differences in characterizing the polarization state of a field by employing either the two- or the three-dimensional coherence-matrix formalism. The extension of the concept of the degree of polarization to include electromagnetic fields having structures of arbitrary form is expected to be particularly useful, for example, in near-field optics.

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Keywords

polarization, degree of polarization, optical near fields, electromagnetic fields

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Citation

Setälä, Tero & Shevchenko, Andriy & Kaivola, Matti & Friberg, Ari T.. 2002. Degree of polarization for optical near fields. Physical Review E. Volume 66, Issue 1, 016615. ISSN 1550-2376 (electronic). ISSN 1539-3755 (printed). DOI: 10.1103/PhysRevE.66.016615.