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Ultrasensitive terahertz sensing with high-Q toroidal dipole resonance governed by bound states in the continuum in all-dielectric metasurface

Nanophotonics, ISSN: 2192-8614, Vol: 10, Issue: 2, Page: 1295-1307
2021
  • 229
    Citations
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  • 74
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Metric Options:   Counts1 Year3 Year

Metrics Details

  • Citations
    229
    • Citation Indexes
      229
  • Captures
    74

Article Description

Toroidal dipole (TD) with weak coupling to the electromagnetic fields offers tremendous potential for advanced design of photonic devices. However, the excitation of high quality (Q) factor TD resonances in these devices is challenging. Here, we investigate ultrahigh-Q factor TD resonances at terahertz frequencies arising from a distortion of symmetry-protected bound states in the continuum (BIC) in all-dielectric metasurface consisting of an array of high-index tetramer clusters. By elaborately arranging the cylinders forming an asymmetric cluster, two distinct TD resonances governed by BIC are excited and identified. One is distinguished as intracluster TD mode that occurs in the interior of tetramer cluster, and the other one is intercluster TD mode that arises from the two neighboring clusters. Such TD resonances can be turned into ultrahigh-Q leaky resonances by controlling the asymmetry of cluster. The low-loss TD resonances with extremely narrow linewidth are very sensitive to the change in the refractive index of the surrounding media, achieving ultrahigh sensitivity level of 489 GHz/RIU. These findings will open up an avenue to develop ultrasensitive photonic sensor in the terahertz regime.

Bibliographic Details

Yulin Wang; Yong Du; Jianyuan Qin; Zhanghua Han

Walter de Gruyter GmbH

Biochemistry, Genetics and Molecular Biology; Materials Science; Physics and Astronomy; Engineering

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