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Chiral germanium micro-gears for tuning orbital angular momentum

Chiral germanium micro-gears for tuning orbital angular momentum
Chiral germanium micro-gears for tuning orbital angular momentum
Group IV light sources with vertical emission and non-zero orbital-angular momentum (OAM) promise to unlock many novel applications. In this report, we demonstrate cylindrically symmetrical germanium micro-gear cavities, fabricated by etching a grating around the circumference of standard micro-disks, with periods ranging from 14 to 22. Photoluminescence (PL) measurements were done to identify the confined whispering-gallery modes (WGM). Finite-difference time-domain (FDTD) simulations were conducted to map the resonant modes to their modal profiles and characteristics. Vertical emission of WGMs with non-zero OAM was demonstrated, with a clear dependence of the OAM order (ℓ) on the WGM azimuthal order and the number of micro-gear grating periods. As the chirality, or the direction of rotation, is not controlled in a symmetrical cavity, we propose introducing staircase or triangular-shaped gear periods resulting in an asymmetry. By choosing the diameter, number of periods, and the asymmetrical direction of the gear-teeth, it is possible to generate OAM signals with certain wavelength, OAM order and chirality.
2045-2322
Al-Attili, Abdelrahman Zaher
534a1c1f-3f8c-4a78-b71b-50c156e23373
Burt, Daniel
49c801a2-fb48-40f2-b72f-f713151b96e6
Li, Zuo
05f14f5e-fc6e-446e-ac52-64be640b5e42
Higashitarumizu, Naoki
745b7d3e-e723-4fc5-9cf0-b763a8d216d6
Gardes, Frederic
7a49fc6d-dade-4099-b016-c60737cb5bb2
Ishikawa, Yasuhiko
e969492d-8143-4aca-9f9c-af4de65b7377
Saito, Shinichi
14a5d20b-055e-4f48-9dda-267e88bd3fdc
Al-Attili, Abdelrahman Zaher
534a1c1f-3f8c-4a78-b71b-50c156e23373
Burt, Daniel
49c801a2-fb48-40f2-b72f-f713151b96e6
Li, Zuo
05f14f5e-fc6e-446e-ac52-64be640b5e42
Higashitarumizu, Naoki
745b7d3e-e723-4fc5-9cf0-b763a8d216d6
Gardes, Frederic
7a49fc6d-dade-4099-b016-c60737cb5bb2
Ishikawa, Yasuhiko
e969492d-8143-4aca-9f9c-af4de65b7377
Saito, Shinichi
14a5d20b-055e-4f48-9dda-267e88bd3fdc

Al-Attili, Abdelrahman Zaher, Burt, Daniel, Li, Zuo, Higashitarumizu, Naoki, Gardes, Frederic, Ishikawa, Yasuhiko and Saito, Shinichi (2022) Chiral germanium micro-gears for tuning orbital angular momentum. Scientific Reports, 12 (1), [7465]. (doi:10.1038/s41598-022-11245-1).

Record type: Article

Abstract

Group IV light sources with vertical emission and non-zero orbital-angular momentum (OAM) promise to unlock many novel applications. In this report, we demonstrate cylindrically symmetrical germanium micro-gear cavities, fabricated by etching a grating around the circumference of standard micro-disks, with periods ranging from 14 to 22. Photoluminescence (PL) measurements were done to identify the confined whispering-gallery modes (WGM). Finite-difference time-domain (FDTD) simulations were conducted to map the resonant modes to their modal profiles and characteristics. Vertical emission of WGMs with non-zero OAM was demonstrated, with a clear dependence of the OAM order (ℓ) on the WGM azimuthal order and the number of micro-gear grating periods. As the chirality, or the direction of rotation, is not controlled in a symmetrical cavity, we propose introducing staircase or triangular-shaped gear periods resulting in an asymmetry. By choosing the diameter, number of periods, and the asymmetrical direction of the gear-teeth, it is possible to generate OAM signals with certain wavelength, OAM order and chirality.

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s41598-022-11245-1 - Version of Record
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Accepted/In Press date: 20 April 2022
Published date: 6 May 2022
Additional Information: © 2022. The Author(s).

Identifiers

Local EPrints ID: 470932
URI: http://eprints.soton.ac.uk/id/eprint/470932
ISSN: 2045-2322
PURE UUID: 69b8b1ab-c33c-4e1f-84e3-3df824b92bb1
ORCID for Frederic Gardes: ORCID iD orcid.org/0000-0003-1400-3272
ORCID for Shinichi Saito: ORCID iD orcid.org/0000-0003-1539-1182

Catalogue record

Date deposited: 21 Oct 2022 16:33
Last modified: 22 Oct 2022 01:43

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Contributors

Author: Abdelrahman Zaher Al-Attili
Author: Daniel Burt
Author: Zuo Li
Author: Naoki Higashitarumizu
Author: Frederic Gardes ORCID iD
Author: Yasuhiko Ishikawa
Author: Shinichi Saito ORCID iD

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