Extreme Nonreciprocity in Metasurfaces Based on Bound States in the Continuum

Luis Manuel Máñez-Espina*, Ihar Faniayeu, Viktar Asadchy, Ana Díaz-Rubio

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

2 Citations (Scopus)
45 Downloads (Pure)

Abstract

Nonreciprocal devices, including optical isolators, phase shifters, and amplifiers, are pivotal for advanced optical systems. However, exploiting natural materials is challenging due to their weak magneto-optical (MO) effects, requiring substantial thickness to construct effective optical devices. In this study, it is demonstrated that subwavelength metasurfaces supporting bound states in the continuum (BICs) and made of conventional ferrimagnetic material can exhibit strong nonreciprocity in the Faraday configuration and near-unity magnetic circular dichroism (MCD). These metasurfaces enhance the MO effect by 3–4 orders of magnitude compared to a continuous film of the same material. This significant enhancement is achieved by leveraging Huygens' condition in the metasurface whose structural units support paired electric and magnetic dipole resonances. The multi-mode temporal coupled mode theory (CMT) is developed for the observed enhancement of the MO effect, and the findings with the full-wave simulations are confirmed.

Original languageEnglish
Article number2301455
JournalADVANCED OPTICAL MATERIALS
Volume12
Issue number1
Early online date2023
DOIs
Publication statusPublished - 4 Jan 2024
MoE publication typeA1 Journal article-refereed

Keywords

  • bound states in the continuum
  • Faraday rotation
  • magneto-optical effect
  • metasurfaces

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