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Interrogating nanoparticles with focused doughnuts

Interrogating nanoparticles with focused doughnuts
Interrogating nanoparticles with focused doughnuts
The propagation of electromagnetic radiation in free-space is described by the source-free Maxwells equations. In contrast to conventional solutions such as infinite-energy plane waves and Gaus- sian pulses, there exists a family of exact solutions which represent localised transmission of finite electromagnetic energy [1]. One such solution is known as the Focused Doughnut (FD) pulse a peculiar single-cycle electromagnetic perturbation with a unique toroidal field topology and 3-dimensional, polynomial energy localisation [2]. Here, for the first time we present a com- prehensive study of the FD pulse: we investigate the propagation dynamics and interactions of these complex electromagnetic pulses with homogeneous and structured media.

The FD pulse exhibits a number of intriguing properties. Its purely single-cycle nature results in an ultra-broadband frequency spectrum and a well defined spatial-chirp. In fact, the spatial dependence of the pulse is inseparable from its temporal dependence. In addition, the toroidal topology of the pulse gives rise to significant longitudinal field components at the pulse that hold potential for particle acceleration applications [2]. Although the FD pulse has remained a theoretical curiosity since its first prediction, successful experimental realisation could lead to its use in a variety of settings, such as microscopy, communications, directed energy transfer, spectroscopy, and particle trapping and acceleration. Further interest in the FD pulse stems from the burgeoning field of toroidal electrodynamics, owing to the topological similarities between the FD pulse and the near-field configuration of the toroidal dipole excitation [3].

The intriguing light-matter interactions of the FD pulse are examined from several perspectives. We present a full evaluation of the transformations the FD pulse undergoes due to interactions with dielectric and metallic interfaces. This has revealed the unusual behaviour of both the TE and TM pulses under reflection, with respect to the reversal of the azimuthal and radial field components. Furthermore, the interactions of FDs with small dielectric and plasmonic particles are considered, where the broadband nature and complex field topology of the pulses is expected to play a significant role in mode excitation. Recent work has demonstrated broad modal excitation within the nanostructures and distinct differences between the interaction with TE and TM pulses. Possible experimental realisations of these complex electromagnetic perturbations resulting from the theoretical/computational treatment presented here will be discussed.
Raybould, T.A.
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Fedotov, V.A.
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Papasimakis, N.
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Youngs, I.
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Zheludev, N.I.
32fb6af7-97e4-4d11-bca6-805745e40cc6
Raybould, T.A.
cd82c867-4261-44fa-ac5e-b1e537b6958f
Fedotov, V.A.
3725f5cc-2d0b-4e61-95c5-26d187c84f25
Papasimakis, N.
f416bfa9-544c-4a3e-8a2d-bc1c11133a51
Youngs, I.
a057ce4a-7764-45c3-9b08-55ac3e6765e6
Zheludev, N.I.
32fb6af7-97e4-4d11-bca6-805745e40cc6

Raybould, T.A., Fedotov, V.A., Papasimakis, N., Youngs, I. and Zheludev, N.I. (2015) Interrogating nanoparticles with focused doughnuts. Progress In Electromagnetics Research Symposium (PIERS 2015), Czech Republic. 06 - 09 Jul 2015. 1 pp .

Record type: Conference or Workshop Item (Other)

Abstract

The propagation of electromagnetic radiation in free-space is described by the source-free Maxwells equations. In contrast to conventional solutions such as infinite-energy plane waves and Gaus- sian pulses, there exists a family of exact solutions which represent localised transmission of finite electromagnetic energy [1]. One such solution is known as the Focused Doughnut (FD) pulse a peculiar single-cycle electromagnetic perturbation with a unique toroidal field topology and 3-dimensional, polynomial energy localisation [2]. Here, for the first time we present a com- prehensive study of the FD pulse: we investigate the propagation dynamics and interactions of these complex electromagnetic pulses with homogeneous and structured media.

The FD pulse exhibits a number of intriguing properties. Its purely single-cycle nature results in an ultra-broadband frequency spectrum and a well defined spatial-chirp. In fact, the spatial dependence of the pulse is inseparable from its temporal dependence. In addition, the toroidal topology of the pulse gives rise to significant longitudinal field components at the pulse that hold potential for particle acceleration applications [2]. Although the FD pulse has remained a theoretical curiosity since its first prediction, successful experimental realisation could lead to its use in a variety of settings, such as microscopy, communications, directed energy transfer, spectroscopy, and particle trapping and acceleration. Further interest in the FD pulse stems from the burgeoning field of toroidal electrodynamics, owing to the topological similarities between the FD pulse and the near-field configuration of the toroidal dipole excitation [3].

The intriguing light-matter interactions of the FD pulse are examined from several perspectives. We present a full evaluation of the transformations the FD pulse undergoes due to interactions with dielectric and metallic interfaces. This has revealed the unusual behaviour of both the TE and TM pulses under reflection, with respect to the reversal of the azimuthal and radial field components. Furthermore, the interactions of FDs with small dielectric and plasmonic particles are considered, where the broadband nature and complex field topology of the pulses is expected to play a significant role in mode excitation. Recent work has demonstrated broad modal excitation within the nanostructures and distinct differences between the interaction with TE and TM pulses. Possible experimental realisations of these complex electromagnetic perturbations resulting from the theoretical/computational treatment presented here will be discussed.

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Published date: 8 July 2015
Venue - Dates: Progress In Electromagnetics Research Symposium (PIERS 2015), Czech Republic, 2015-07-06 - 2015-07-09
Organisations: Optoelectronics Research Centre

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Local EPrints ID: 379510
URI: https://eprints.soton.ac.uk/id/eprint/379510
PURE UUID: e3db9756-9cd9-4206-b344-638de94c56f9
ORCID for N. Papasimakis: ORCID iD orcid.org/0000-0002-6347-6466
ORCID for N.I. Zheludev: ORCID iD orcid.org/0000-0002-1013-6636

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Date deposited: 03 Aug 2015 11:02
Last modified: 16 Nov 2018 01:36

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Contributors

Author: T.A. Raybould
Author: V.A. Fedotov
Author: N. Papasimakis ORCID iD
Author: I. Youngs
Author: N.I. Zheludev ORCID iD

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