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Journal of Nanophotonics

Optimization of structure parameters of concentric plasmonic lens for 355 nm radially polarized illumination
Author(s): Jiaxin Ji; Yonggang Meng; Jun Zhang
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Paper Abstract

We propose and optimize two designs of plasmonic lens structures, concentric grooves with a central hole (CGH) and concentric grooves with a central pillar (CGP), based on a traditional structure of concentric grooves (CG). The numerical investigation based on COMSOL Multiphysics is performed to optimize the three kinds of structures by a 355 nm radially polarized laser illumination. It is found that full-width at half maximum (FWHM) is closely related to the size of the center-position, and the field enhancement effect depends on the resonant wavelength of surface plasmon polaritons, permittivity, film thickness, and groove number. Compared to a FWHM of λ/3 (λ is the wavelength of the laser beam) with the conventional CG type, the combination of localized and extended surface plasmons results in CGP and CGH parameters achieving their optimal value with a much smaller spot size of λ/8 and higher intensity enhancement for a variety of the aspect ratios of central pillar and hole. A focused ion beam was used to fabricate the three type nanostructures with high accuracy. The CGH type with a central hole 20.88 nm in diameter and the CGP type with a central pillar 55.45 nm in diameter have been successfully fabricated approximately to their optimization results.

Paper Details

Date Published: 8 January 2015
PDF: 10 pages
J. Nanophoton. 9(1) 093794 doi: 10.1117/1.JNP.9.093794
Published in: Journal of Nanophotonics Volume 9, Issue 1
Show Author Affiliations
Jiaxin Ji, Tsinghua Univ. (China)
Yonggang Meng, Tsinghua Univ. (China)
Jun Zhang, Tsinghua Univ. (China)

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