Toroidal and magnetic Fano resonances in planar THz metamaterials

The toroidal dipole moment, a localized electromagnetic excitation of torus magnetic fields, has been observed experimentally in metamaterials. However, the metamaterial based toroidal moment was restricted at higher frequencies by the complex three-dimensional structure. Recently, it has been shown...

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Main Authors: Srivastava, Yogesh Kumar, Han, Song, Gupta, Manoj, Cong, Longqing, Singh, Ranjan
Other Authors: School of Physical and Mathematical Sciences
Format: Article
Language:English
Published: 2017
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Online Access:https://hdl.handle.net/10356/86829
http://hdl.handle.net/10220/44219
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-868292023-02-28T19:34:16Z Toroidal and magnetic Fano resonances in planar THz metamaterials Srivastava, Yogesh Kumar Han, Song Gupta, Manoj Cong, Longqing Singh, Ranjan School of Physical and Mathematical Sciences Centre for Disruptive Photonic Technologies (CDPT) The Photonics Institute Quantum Field Theory Electromagnetic Radiation The toroidal dipole moment, a localized electromagnetic excitation of torus magnetic fields, has been observed experimentally in metamaterials. However, the metamaterial based toroidal moment was restricted at higher frequencies by the complex three-dimensional structure. Recently, it has been shown that toroidal moment could also be excited in a planar metamaterial structure. Here, we use asymmetric Fano resonators to illustrate theoretically and experimentally the underlying physics of the toroidal coupling in an array of planar metamaterials. It is observed that the anti-parallel magnetic moment configuration shows toroidal excitation with higher quality (Q) factor Fano resonance, while the parallel magnetic moment shows relatively lower Q factor resonance. Moreover, the electric and toroidal dipole interferes destructively to give rise to an anapole excitation. The magnetic dipole-dipole interaction is employed to understand the differences between the toroidal and magnetic Fano resonances. We further study the impact of intra unit-cell coupling between the Fano resonator pairs in the mirrored and non-mirrored arrangements. The numerical and theoretical approach for modelling the near-field effects and experimental demonstration of toroidal and magnetic Fano resonances in planar systems are particularly promising for tailoring the loss in metamaterials across a broad range of the electromagnetic spectrum. MOE (Min. of Education, S’pore) Published version 2017-12-28T06:33:56Z 2019-12-06T16:29:47Z 2017-12-28T06:33:56Z 2019-12-06T16:29:47Z 2017 Journal Article Han, S., Gupta, M., Cong, L., Srivastava, Y. K., & Singh, R. (2017). Toroidal and magnetic Fano resonances in planar THz metamaterials. Journal of Applied Physics, 122(11), 113105-. 0021-8979 https://hdl.handle.net/10356/86829 http://hdl.handle.net/10220/44219 10.1063/1.5001246 en Journal of Applied Physics © 2017 The Authors (Published by AIP Publishing). This paper was published in Journal of Applied Physics and is made available as an electronic reprint (preprint) with permission of The Authors (Published by AIP Publishing). The published version is available at:[http://dx.doi.org/10.1063/1.5001246]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law. 8 p. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Quantum Field Theory
Electromagnetic Radiation
spellingShingle Quantum Field Theory
Electromagnetic Radiation
Srivastava, Yogesh Kumar
Han, Song
Gupta, Manoj
Cong, Longqing
Singh, Ranjan
Toroidal and magnetic Fano resonances in planar THz metamaterials
description The toroidal dipole moment, a localized electromagnetic excitation of torus magnetic fields, has been observed experimentally in metamaterials. However, the metamaterial based toroidal moment was restricted at higher frequencies by the complex three-dimensional structure. Recently, it has been shown that toroidal moment could also be excited in a planar metamaterial structure. Here, we use asymmetric Fano resonators to illustrate theoretically and experimentally the underlying physics of the toroidal coupling in an array of planar metamaterials. It is observed that the anti-parallel magnetic moment configuration shows toroidal excitation with higher quality (Q) factor Fano resonance, while the parallel magnetic moment shows relatively lower Q factor resonance. Moreover, the electric and toroidal dipole interferes destructively to give rise to an anapole excitation. The magnetic dipole-dipole interaction is employed to understand the differences between the toroidal and magnetic Fano resonances. We further study the impact of intra unit-cell coupling between the Fano resonator pairs in the mirrored and non-mirrored arrangements. The numerical and theoretical approach for modelling the near-field effects and experimental demonstration of toroidal and magnetic Fano resonances in planar systems are particularly promising for tailoring the loss in metamaterials across a broad range of the electromagnetic spectrum.
author2 School of Physical and Mathematical Sciences
author_facet School of Physical and Mathematical Sciences
Srivastava, Yogesh Kumar
Han, Song
Gupta, Manoj
Cong, Longqing
Singh, Ranjan
format Article
author Srivastava, Yogesh Kumar
Han, Song
Gupta, Manoj
Cong, Longqing
Singh, Ranjan
author_sort Srivastava, Yogesh Kumar
title Toroidal and magnetic Fano resonances in planar THz metamaterials
title_short Toroidal and magnetic Fano resonances in planar THz metamaterials
title_full Toroidal and magnetic Fano resonances in planar THz metamaterials
title_fullStr Toroidal and magnetic Fano resonances in planar THz metamaterials
title_full_unstemmed Toroidal and magnetic Fano resonances in planar THz metamaterials
title_sort toroidal and magnetic fano resonances in planar thz metamaterials
publishDate 2017
url https://hdl.handle.net/10356/86829
http://hdl.handle.net/10220/44219
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