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JOURNALS // Computer Optics // Archive

Computer Optics, 2022 Volume 46, Issue 4, Pages 531–536 (Mi co1043)

This article is cited in 3 papers

DIFFRACTIVE OPTICS, OPTICAL TECHNOLOGIES

Comparison of the shape of focal spots in terms of intensity and energy flux for a high-aperture zone plate and a spiral zone plate

A. A. Savelyevaab, E. S. Kozlovaab

a Image Processing Systems Institute of the RAS - Branch of the FSRC "Crystallography and Photonics" RAS, Samara, Russia, Samara
b Samara National Research University

Abstract: Using a finite-difference time-domain method, it has been shown that focal spots generated when tightly focusing a linearly polarized Gaussian beam by a Fresnel zone plate (FZP) and when focusing a Gaussian beam with an embedded optical vortex by a spiral zone plate (SZP) have different patterns of the intensity and energy flux. The most significant differences are observed when the value of the topological charge (TC) is equal to three. The energy flux has an annular distribution when the Gaussian beam is focused by the FZP, while the SZP produces a field whose patterns of intensity and energy flux have three local maxima. The number of local maxima corresponds to the order of the SZP. At a certain distance from the focus, the petal structure of the intensity (and energy flux) changes to a ring distribution.

Keywords: two-layered dielectric microcylinder, photonic nanojet, tight focusing, FDTD-method

Received: 04.06.2021
Accepted: 05.04.2022

DOI: 10.18287/2412-6179-CO-934



© Steklov Math. Inst. of RAS, 2024