Plasmonic effects in near-field optical transmission enhancement through a single bowtie-shaped aperture |
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Authors: | EX Jin X Xu |
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Institution: | (1) School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, USA |
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Abstract: | In this paper, the enhanced optical transmission through a special type of aperture of a bowtie shape is investigated through
near-field imaging and finite-difference numerical analysis. Under linear polarizations in two orthogonal directions, the
optical near fields of the bowtie aperture and comparable square and rectangular apertures made in gold and chromium thin
films are measured and compared. The bowtie aperture is able to provide a nanometer-sized optical spot when the incident light
is polarized across the bowtie gap and delivers a considerable amount of light. Localized surface plasmons are clearly observed
in the near-field images for both bowtie and rectangular apertures in gold, but invisible in chromium. Finite-difference time-domain
calculations reveal that, depending on the polarization of the incident light, the unique optical properties of the bowtie
aperture are a result of either the optical waveguide and the coupled surface plasmon polariton modes existing in the bowtie
gap or the coupling between the two open arms of the bowtie aperture.
PACS 81.07.-b; 07.79.Fc; 71.36.+c; 78.66.Bz; 42.79.Gn; 42.79.Vb |
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Keywords: | |
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