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Near-field mapping of the edge mode of a topological valley slab waveguide at λ = 1.55 μm

Near-field mapping of the edge mode of a topological valley slab waveguide at λ = 1.55 μm
Near-field mapping of the edge mode of a topological valley slab waveguide at λ = 1.55 μm
Valley polarized topological states of light allow for robust waveguiding which has been demonstrated for transverse-electric modes in THz and near-infrared parts of the spectrum. As the topological protection relies on guiding the light via a highly structured surface, direct imaging of the photonic modes at sub-unit cell resolution is of high interest but challenging in particular for transverse-magnetic modes. Here, we report mapping the transverse-magnetic modes in a valley photonic crystal waveguide using scattering-type scanning near-field optical microscopy at the optical telecom C-band wavelength. The waveguide based on a triangular air-hole motif with broken inversion symmetry is fabricated from suspended Germanium layer. We observed the launching and guiding of the transverse-magnetic edge mode along the boundary between topologically distinct domains with opposite valley Chern indices. These results are supported by theoretical simulations, and provide insight into the design and use of topological protected states for applications in densely integrated optical telecommunication devices.
0003-6951
Dubrovkin, A.M.
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Chattopadhyay, U.
1e4277f1-8a84-4a37-b978-6aa7c4b740f0
Qiang, Bo
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Buchnev, Oleksandr
60cdb0d2-3388-47be-a066-61b3b396f69d
Wang, Qi Jie
4d00dfbb-4005-47eb-99bb-9ca2fed1459e
Chong, Yidong
84ca5791-58fd-44cd-bf1e-019afda9a379
Zheludev, Nikolai
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Dubrovkin, A.M.
4c6f1807-79d1-4e93-8961-3354fc37853b
Chattopadhyay, U.
1e4277f1-8a84-4a37-b978-6aa7c4b740f0
Qiang, Bo
e92401c1-a870-40c2-91d7-ab70fa7a2ecd
Buchnev, Oleksandr
60cdb0d2-3388-47be-a066-61b3b396f69d
Wang, Qi Jie
4d00dfbb-4005-47eb-99bb-9ca2fed1459e
Chong, Yidong
84ca5791-58fd-44cd-bf1e-019afda9a379
Zheludev, Nikolai
32fb6af7-97e4-4d11-bca6-805745e40cc6

Dubrovkin, A.M., Chattopadhyay, U., Qiang, Bo, Buchnev, Oleksandr, Wang, Qi Jie, Chong, Yidong and Zheludev, Nikolai (2020) Near-field mapping of the edge mode of a topological valley slab waveguide at λ = 1.55 μm. Applied Physics Letters, 116 (19), [191105]. (doi:10.1063/5.0004390).

Record type: Article

Abstract

Valley polarized topological states of light allow for robust waveguiding which has been demonstrated for transverse-electric modes in THz and near-infrared parts of the spectrum. As the topological protection relies on guiding the light via a highly structured surface, direct imaging of the photonic modes at sub-unit cell resolution is of high interest but challenging in particular for transverse-magnetic modes. Here, we report mapping the transverse-magnetic modes in a valley photonic crystal waveguide using scattering-type scanning near-field optical microscopy at the optical telecom C-band wavelength. The waveguide based on a triangular air-hole motif with broken inversion symmetry is fabricated from suspended Germanium layer. We observed the launching and guiding of the transverse-magnetic edge mode along the boundary between topologically distinct domains with opposite valley Chern indices. These results are supported by theoretical simulations, and provide insight into the design and use of topological protected states for applications in densely integrated optical telecommunication devices.

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Near-field mapping of the edge mode of a topological valley slab waveguide at - Accepted Manuscript
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Accepted/In Press date: 20 April 2020
e-pub ahead of print date: 13 May 2020
Published date: 2020

Identifiers

Local EPrints ID: 439710
URI: http://eprints.soton.ac.uk/id/eprint/439710
ISSN: 0003-6951
PURE UUID: 7f63b75d-936e-40ee-b6b6-7a9015d1f2f5
ORCID for Nikolai Zheludev: ORCID iD orcid.org/0000-0002-1013-6636

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Date deposited: 30 Apr 2020 16:30
Last modified: 29 Jul 2020 01:31

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