Spin texture and chiral coupling of circularly polarized dipole field

We show that a circularly polarized electric dipole harbors a near-field concentrated wave which orbits around with an energy flux significantly larger (five orders of magnitudes at ∼1 nm radial distance) than far-field radiation. This near-field wave is found to carry transverse spins and reveal sk...

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Main Authors: Shi Yu, Kim Hong Koo
Format: Article
Language:English
Published: De Gruyter 2023-01-01
Series:Nanophotonics
Subjects:
Online Access:https://doi.org/10.1515/nanoph-2022-0581
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author Shi Yu
Kim Hong Koo
author_facet Shi Yu
Kim Hong Koo
author_sort Shi Yu
collection DOAJ
description We show that a circularly polarized electric dipole harbors a near-field concentrated wave which orbits around with an energy flux significantly larger (five orders of magnitudes at ∼1 nm radial distance) than far-field radiation. This near-field wave is found to carry transverse spins and reveal skyrmion spin texture (Néel-type). By performing electromagnetic analysis and numerical simulation, we demonstrate chiral extraction of a near-field rotational energy flux: the confined energy flow is out-coupled to surface plasmons on metal surface, whose curvature is designed to provide orbital angular momentum matched to spin angular momentum of dipole field, that is, to facilitate spin–orbit interaction. Strong coupling occurs with high chiral selectivity (∼113) and Purcell enhancement (∼17) when both linear and angular momenta are matched between dipole field and surface plasmons. Existence of a high-intensity energy flux in the deep-bottom near-field region (r ∼ 1 nm) opens up an interesting avenue in altering fundamental properties of dipole emission. For example, extracting ∼1% of this flux would result in enhancing spontaneous emission rate by ∼1000 times.
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spelling doaj.art-09608cc7dbe14f9396f2c8f2dd28aada2023-02-05T08:27:17ZengDe GruyterNanophotonics2192-86142023-01-0112112913810.1515/nanoph-2022-0581Spin texture and chiral coupling of circularly polarized dipole fieldShi Yu0Kim Hong Koo1Department of Electrical and Computer Engineering and Petersen Institute of NanoScience and Engineering, University of Pittsburgh, Pittsburgh, PA15261, USADepartment of Electrical and Computer Engineering and Petersen Institute of NanoScience and Engineering, University of Pittsburgh, Pittsburgh, PA15261, USAWe show that a circularly polarized electric dipole harbors a near-field concentrated wave which orbits around with an energy flux significantly larger (five orders of magnitudes at ∼1 nm radial distance) than far-field radiation. This near-field wave is found to carry transverse spins and reveal skyrmion spin texture (Néel-type). By performing electromagnetic analysis and numerical simulation, we demonstrate chiral extraction of a near-field rotational energy flux: the confined energy flow is out-coupled to surface plasmons on metal surface, whose curvature is designed to provide orbital angular momentum matched to spin angular momentum of dipole field, that is, to facilitate spin–orbit interaction. Strong coupling occurs with high chiral selectivity (∼113) and Purcell enhancement (∼17) when both linear and angular momenta are matched between dipole field and surface plasmons. Existence of a high-intensity energy flux in the deep-bottom near-field region (r ∼ 1 nm) opens up an interesting avenue in altering fundamental properties of dipole emission. For example, extracting ∼1% of this flux would result in enhancing spontaneous emission rate by ∼1000 times.https://doi.org/10.1515/nanoph-2022-0581chiral couplingdipole near-field waveplasmonic waveguides
spellingShingle Shi Yu
Kim Hong Koo
Spin texture and chiral coupling of circularly polarized dipole field
Nanophotonics
chiral coupling
dipole near-field wave
plasmonic waveguides
title Spin texture and chiral coupling of circularly polarized dipole field
title_full Spin texture and chiral coupling of circularly polarized dipole field
title_fullStr Spin texture and chiral coupling of circularly polarized dipole field
title_full_unstemmed Spin texture and chiral coupling of circularly polarized dipole field
title_short Spin texture and chiral coupling of circularly polarized dipole field
title_sort spin texture and chiral coupling of circularly polarized dipole field
topic chiral coupling
dipole near-field wave
plasmonic waveguides
url https://doi.org/10.1515/nanoph-2022-0581
work_keys_str_mv AT shiyu spintextureandchiralcouplingofcircularlypolarizeddipolefield
AT kimhongkoo spintextureandchiralcouplingofcircularlypolarizeddipolefield