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Directional conversion of a THz propagating wave into surface waves in deformable metagratings

Directional conversion of a THz propagating wave into surface waves in deformable metagratings
Directional conversion of a THz propagating wave into surface waves in deformable metagratings
Controllable conversion between propagating light waves and surface waves (SWs) has recently attracted significant research interests. This paper demonstrates, via numerical simulation, for the first time all-dielectric SW converters that possess a tunable and directional SW conversion efficiency. The SW converters contain multiple metagratings of Si pillars embedded in a deformable substrate. In the analysis, an infinitely large, bi-periodic metagrating under the illumination of linearly polarized light is considered first. The SW conversion efficiency of this metagrating can be modulated between 4.3% and 51.0% for incident light frequency at 0.8 THz by stretching the deformable substrate along the direction of SW propagation. Subsequently, two SW converters under circularly polarized light illumination are analyzed, where a similar level of efficiency modulation is retained in finite-sized metagratings. In these converters, only the metagrating channels along the stretch direction have a strong SW conversion efficiency, which can reach 40.4% after normalization against the effective grating area. The directivity, a parameter defined here to reveal the energy contrast among the output channels, reaches 38.6 in one of the converters. Due to its high tunability, high directivity and compact size, the SW converters may be used as tunable optical sensors and light couplers in the THz regime.
1094-4087
21749-21762
Liu, Jiaming
1fad0248-35f1-4613-a32f-c319a11835ce
Fang, Xu
96b4b212-496b-4d68-82a4-06df70f94a86
He, Fei
0b5b12e2-82ec-407b-8e4f-a8ba024d9fb3
Yin, Shengqi
363a868e-95cb-4354-b52f-0d4f9fcd3e70
Lyu, Wen
e8760cff-7838-4e84-b76e-07337f0619ee
Geng, Hua
4de0000a-a809-4b66-81bb-ea0befdad671
Deng, Xiaojiao
ccb9674c-95f0-43cb-b09b-5af200c85318
Zheng, Xiaoping
81475ce2-f9d2-4173-81de-b95083c90b29
Liu, Jiaming
1fad0248-35f1-4613-a32f-c319a11835ce
Fang, Xu
96b4b212-496b-4d68-82a4-06df70f94a86
He, Fei
0b5b12e2-82ec-407b-8e4f-a8ba024d9fb3
Yin, Shengqi
363a868e-95cb-4354-b52f-0d4f9fcd3e70
Lyu, Wen
e8760cff-7838-4e84-b76e-07337f0619ee
Geng, Hua
4de0000a-a809-4b66-81bb-ea0befdad671
Deng, Xiaojiao
ccb9674c-95f0-43cb-b09b-5af200c85318
Zheng, Xiaoping
81475ce2-f9d2-4173-81de-b95083c90b29

Liu, Jiaming, Fang, Xu, He, Fei, Yin, Shengqi, Lyu, Wen, Geng, Hua, Deng, Xiaojiao and Zheng, Xiaoping (2021) Directional conversion of a THz propagating wave into surface waves in deformable metagratings. Optics Express, 29 (14), 21749-21762. (doi:10.1364/OE.431817).

Record type: Article

Abstract

Controllable conversion between propagating light waves and surface waves (SWs) has recently attracted significant research interests. This paper demonstrates, via numerical simulation, for the first time all-dielectric SW converters that possess a tunable and directional SW conversion efficiency. The SW converters contain multiple metagratings of Si pillars embedded in a deformable substrate. In the analysis, an infinitely large, bi-periodic metagrating under the illumination of linearly polarized light is considered first. The SW conversion efficiency of this metagrating can be modulated between 4.3% and 51.0% for incident light frequency at 0.8 THz by stretching the deformable substrate along the direction of SW propagation. Subsequently, two SW converters under circularly polarized light illumination are analyzed, where a similar level of efficiency modulation is retained in finite-sized metagratings. In these converters, only the metagrating channels along the stretch direction have a strong SW conversion efficiency, which can reach 40.4% after normalization against the effective grating area. The directivity, a parameter defined here to reveal the energy contrast among the output channels, reaches 38.6 in one of the converters. Due to its high tunability, high directivity and compact size, the SW converters may be used as tunable optical sensors and light couplers in the THz regime.

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Published date: 24 June 2021

Identifiers

Local EPrints ID: 451811
URI: http://eprints.soton.ac.uk/id/eprint/451811
ISSN: 1094-4087
PURE UUID: 73417b62-a3af-49d5-a06d-16ae69f4773a
ORCID for Xu Fang: ORCID iD orcid.org/0000-0003-1735-2654

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Date deposited: 28 Oct 2021 16:33
Last modified: 11 Aug 2022 01:45

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Contributors

Author: Jiaming Liu
Author: Xu Fang ORCID iD
Author: Fei He
Author: Shengqi Yin
Author: Wen Lyu
Author: Hua Geng
Author: Xiaojiao Deng
Author: Xiaoping Zheng

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