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Calm YM, D'Imperio L, Nesbitt NT, Merlo JM, Rose AH, Yang C, Kempa K, Burns MJ, Naughton MJ. Optical confinement in the nanocoax: coupling to the fundamental TEM-like mode. OPTICS EXPRESS 2020; 28:32152-32164. [PMID: 33115178 DOI: 10.1364/oe.402723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 09/11/2020] [Indexed: 06/11/2023]
Abstract
The nanoscale coaxial cable (nanocoax) has demonstrated optical confinement in the visible and the near infrared. We report on a novel nanofabrication process which yields optically addressable, sub-µm diameter, and high aspect ratio metal-insulator-metal nanocoaxes made by atomic layer deposition of Pt and Al2O3. We observe sub-diffraction-limited optical transmission via the fundamental, TEM-like mode by excitation with a radially polarized optical vortex beam. Our experimental results are based on interrogation with a polarimetric imager. Finite element method numerical simulations support these results, and their uniaxial symmetry was exploited to model taper geometries with both an electrically large volume, (15λ)3, and a nanoscopic exit aperture, (λ/200)2.
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Rajasekharan R, Roberts A. Optical 'magnetic mirror' metasurfaces using interference between Fabry-Pérot cavity resonances in coaxial apertures. Sci Rep 2015; 5:10297. [PMID: 26020728 PMCID: PMC4446991 DOI: 10.1038/srep10297] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 04/07/2015] [Indexed: 11/08/2022] Open
Abstract
Here we propose and computationally demonstrate a quasi-planar metasurface consisting of arrays of pairs of concentric coaxial apertures in a metallic film. The structure relies on destructive interference between Fabry-Pérot modes excited in each aperture at resonance producing transmitted fields that interfere destructively leading to suppressed transmission. Conversely, we show that in the case of a perfect conductor, near-perfect, broadband reflection can be achieved with zero phase change in the electric field and a variation of 2π on passing through the coincident resonances. Extending the concept to shorter wavelengths, we show that mirrors exhibiting close to a 2π phase excursion, albeit with a reduction in the amplitude reflection coefficient at resonance and a lower Q, can be also achieved. Structures such as these can be used to enhance light-matter interactions at surfaces and act as high impedance ground planes for antenna applications.
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Affiliation(s)
- Ranjith Rajasekharan
- Department of Electrical and Electronic Engineering, The University of Melbourne, Victoria, 3010, Australia
| | - Ann Roberts
- School of Physics, The University of Melbourne, Victoria, 3010, Australia
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Srivastava SK, Abdulhalim I. Self-referenced sensor utilizing extra-ordinary optical transmission from metal nanoslits array. OPTICS LETTERS 2015; 40:2425-2428. [PMID: 26393756 DOI: 10.1364/ol.40.002425] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report the first self-referenced sensor based on the extraordinary optical transmission (EOT) of metal-nanoslits array in the near-infra-red (NIR) telecommunication window of the electromagnetic spectrum. The nanoslits array shows two enhanced transmission peaks, out of which one shows a red shift with an increase in the refractive index of the analyte medium, while the other remains fixed. We demonstrate the detection of small amounts of water in ethanol using the nanoslits array chip. The present study might be useful in developing ultra-small biosensor chips integrated to optical fibers for online monitoring and remote sensing applications.
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Abstract
Here we present a strategy for designing wave plates utilizing resonances of subwavelength apertures in metallic films. Specifically, we show that it is possible to tune the geometry in a periodic array of cross-shaped apertures in a silver film to produce a quarter-wave plate at a particular wavelength in the near-infrared. This is achieved by introducing an asymmetry into the lengths of the arms of the crosses.
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Affiliation(s)
- A Roberts
- School of Physics, University of Melbourne, Victoria, 3010, Australia.
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Lehr D, Dietrich K, Helgert C, Käsebier T, Fuchs HJ, Tünnermann A, Kley EB. Plasmonic properties of aluminum nanorings generated by double patterning. OPTICS LETTERS 2012; 37:157-9. [PMID: 22854452 DOI: 10.1364/ol.37.000157] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
In this Letter we evaluate a technique for the efficient and flexible generation of aluminum nanorings based on double patterning and variable shaped electron beam lithography. The process is demonstrated by realizing nanorings with diameters down to 90 nm and feature sizes of 30 nm utilizing a writing speed of one ring per microsecond. Because of redepositions caused by involved etching processes, the material of the rings and, therefore, the impact on the plasmonic properties, are unknown. This issue, which is commonly encountered when metals are nanostructured, is solved by adapting a realistic simulation model that accounts for geometry details and effective material properties. Based on this model, the redepositions are quantified, the plasmonic properties are investigated, and a design tool for the very general class of nanofabrication techniques involving the etching of metals is provided.
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Affiliation(s)
- Dennis Lehr
- Institute of Applied Physics, Friedrich-Schiller-Universität Jena, Jena, Germany.
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Lerman GM, Grajower M, Yanai A, Levy U. Light transmission through a circular metallic grating under broadband radial and azimuthal polarization illumination. OPTICS LETTERS 2011; 36:3972-3974. [PMID: 22002356 DOI: 10.1364/ol.36.003972] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We studied the characteristics of a circular metallic grating illuminated by broadband radial and azimuthal polarizations. We demonstrated that this scenario is the cylindrical analogue of a one-dimensional Cartesian grating illuminated by TM and TE polarizations. We measured the transmission spectra of this structure and observed strong polarization selectivity and, specifically, a resonance for radial polarization excitation, indicating a strong coupling to surface plasmons. The structure may be attractive for applications where pure radial polarization is needed, such as tight focusing, material processing, and particle trapping.
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Affiliation(s)
- Gilad M Lerman
- Department of Applied Physics, The Benin School of Engineering and Computer Science, The Hebrew University of Jerusalem, Jerusalem, Israel.
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Heshmat B, Li D, Darcie TE, Gordon R. Tuning plasmonic resonances of an annular aperture in metal plate. OPTICS EXPRESS 2011; 19:5912-5923. [PMID: 21451616 DOI: 10.1364/oe.19.005912] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We present theory to describe the plasmonic resonances of a subwavelength annular aperture in a real metal plate. The theory provides the reflection, including the amplitude and phase, of radially polarized surface plasmon waves from the end faces of the aperture with a significant departure from the perfect electric conductor case due to plasmonic effects. Oscillations in the reflection amplitude and phase are observed. These oscillations arise from transverse resonances and depend on the geometry of the annulus. The theory is applied to the design of various aperture structures operating at the same resonance wavelength, and it is confirmed by comprehensive electromagnetic simulations. The results are contrasted to the perfect electric conductor case and they will be of significant interest to emerging applications in metamaterials, plasmonic sensors, and near-field optics.
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Affiliation(s)
- Barmak Heshmat
- Department of Electrical and Computer Engineering, University of Victoria, Victoria, British Columbia, Canada
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Baida F, Belkhir A, Arar O, Barakat E, Dahdah J, Chemrouk C, Van Labeke D, Diebold C, Perry N, Bernal MP. Enhanced optical transmission by light coaxing: Mechanism of the TEM-mode excitation. Micron 2010; 41:742-5. [DOI: 10.1016/j.micron.2010.06.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Revised: 06/18/2010] [Accepted: 06/18/2010] [Indexed: 11/26/2022]
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Lin L, Goh XM, McGuinness LP, Roberts A. Plasmonic lenses formed by two-dimensional nanometric cross-shaped aperture arrays for Fresnel-region focusing. NANO LETTERS 2010; 10:1936-1940. [PMID: 20402522 DOI: 10.1021/nl1009712] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We present the experimental demonstration of what are to our knowledge the first two-dimensional planar plasmonic lenses formed by an array of spatially varying cross-shaped apertures in a metallic film for Fresnel-region focusing. The design utilizes localized surface plasmon resonances occurring inside the apertures, accompanied by an aperture geometry dependent phase shift, to achieve the desired spatial phase modulation in the transmitted field. The performance of lenses with different design configurations was evaluated using a confocal scanning optical microscope, and the effects of diffraction on the optical response of these microscale devices are discussed.
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Affiliation(s)
- Ling Lin
- School of Physics, The University of Melbourne, Vic, Australia
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Lu X, Han J, Zhang W. Transmission field enhancement of terahertz pulses in plasmonic, rectangular coaxial geometries. OPTICS LETTERS 2010; 35:904-906. [PMID: 20364164 DOI: 10.1364/ol.35.000904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We report on anomalous field enhancement of terahertz transmission in metallic, rectangular coaxial geometries. The integration of a particle in the hole not only results in a factor of eight increase in normalized transmittance compared to that of the hole-only counterpart, but it also tailors polarization-dependent transmission discrepancy encountered in arrays of rectangular holes. Our experimental and numerical studies on the impact of geometrical dimensions of the integrated particles indicate that dipolar localized surface plasmons of the particles contribute substantially to the terahertz field enhancement through coupling with surface plasmons and localized surface plasmons of the holes.
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Affiliation(s)
- Xinchao Lu
- School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, Oklahoma 74078, USA
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Abstract
Transmission of beams through arrays of coaxial apertures in a thick, perfectly conducting screen is investigated using an angular spectrum approach. It is shown that the transfer function of the screen is complex and strongly dependent on the wavelength and polarization of the incident field and the geometric properties of the screen. Examples of changes in the angular spectrum composition of linearly, radially and azimuthally polarized beams as well as near-field intensity patterns are presented and the role played by different resonant transmission mechanisms discussed.
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Affiliation(s)
- A Roberts
- School of Physics, The University of Melbourne, Victoria 3010, Australia.
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