A Terahertz vortex beam emitter with tunable topological charge and harmonic excitation

Zhang, Zi-Wen and Du, Chaohai and Zhu, Juan-Feng and Han, Feng-Yuan and Li, Fan-Hong and Gao, Zi-Chao and Zhang, Liang and Cross, Adrian W. and Liu, Pu-Kun (2021) A Terahertz vortex beam emitter with tunable topological charge and harmonic excitation. Journal of Lightwave Technology, 39 (19). pp. 6231-6238. ISSN 0733-8724 (https://doi.org/10.1109/JLT.2021.3096727)

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Abstract

Terahertz (THz) vortex beams carrying orbital angular momentum (OAM) with high purity and tunable topological charge (TC) will undoubtedly bring extraordinary capacities for advanced imaging or communication systems. We propose a convenient and efficient method to generate a tunable and broadband vortex beam that is excited by superradiant Smith Purcell radiation (SSPR) on a helical grating. This scheme fully explores the advantages of natural broadband evanescent wave carried by the electron beam and the Bloch’s theorem regulated helical periodic systems. An explicit relation is established between the index of the spatial harmonic wave on the grating and the topological charge of the vortex beam. The electron energy in the SSPR can be customized to ignite the specific spatial harmonics and manipulate the OAM beam, accordingly. The separated radiation region also promises the high purity of the OAM spectrum. The harmonic excitation reduces the communality between the wavelength and the device size and alleviates the difficulty of device fabrication in the THz band. The proposed vortex scheme can not only be handily scaled to microwave and mid‑infrared regions, but also bring possibilities to applications based on compact tunable vortex beam sources.

ORCID iDs

Zhang, Zi-Wen, Du, Chaohai, Zhu, Juan-Feng, Han, Feng-Yuan, Li, Fan-Hong, Gao, Zi-Chao, Zhang, Liang ORCID logoORCID: https://orcid.org/0000-0002-6317-0395, Cross, Adrian W. ORCID logoORCID: https://orcid.org/0000-0001-7672-1283 and Liu, Pu-Kun;
  • Item type:Article
    ID code:77071
    Dates:
    Date
    Event
    1 October 2021
    Published
    14 July 2021
    Published Online
    9 July 2021
    Accepted
    Notes:© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
    Subjects:Technology > Electrical engineering. Electronics Nuclear engineering
    Department:Faculty of Science > Physics
    Depositing user: Pure Administrator
    Date deposited:13 Jul 2021 15:54
    Last modified:23 Nov 2024 01:16
    URI:https://strathprints.strath.ac.uk/id/eprint/77071
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