Evanescent and propagating fields of a strongly focused beam in the near-field and far-field regions

Nikolai I. Petrov

doi:10.1117/12.2554939

1 April 2020 Evanescent and propagating fields of a strongly focused beam in the near-field and far-field regions

Nikolai I. Petrov

Proceedings Volume 11345, Nanophotonics VIII; 113450X (2020) https://doi.org/10.1117/12.2554939
Event: SPIE Photonics Europe, 2020, Online Only

Abstract

Evanescent and propagating field distributions from a strongly focused wave beam with subwavelength waist w_a << λ as a function of polar angle and distance are investigated. Exact amplitudes and intensities of evanescent E_ev and propagating E_p fields, including interference terms, are presented both in near and far field regions. It is shown that the amplitude of E_ev decays as exp(-r/w_a) in near-field region and evanescent waves do not contribute to the far field in the forward direction as well as in the transverse directions θ = π/2, even though the oscillating evanescent field of the same strength, but opposite in sign to the propagating field, exists in the transverse sheet. A far-field method for characterizing apertures based on the relationship between the relative intensity of propagating modes and a subwavelength aperture diameter is proposed.

Conference Presentation

Citation Download Citation

Nikolai I. Petrov "Evanescent and propagating fields of a strongly focused beam in the near-field and far-field regions", Proc. SPIE 11345, Nanophotonics VIII, 113450X (1 April 2020); https://doi.org/10.1117/12.2554939

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