Bound states in the continuum in asymmetric dielectric metasurfaces

Zhou, C., Huang, L., Jin, R., Xu, L. ORCID: 0000-0001-9071-4311, Li, G., Rahmani, M. ORCID: 0000-0001-9268-4793, Chen, X., Lu, W. and Miroshnichenko, A.E., 2023. Bound states in the continuum in asymmetric dielectric metasurfaces. Laser and Photonics Reviews, 17 (3): 2200564. ISSN 1863-8880

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It is well established that for symmetry-protected bound states in the continuum (BICs), introducing the broken geometry symmetry in a dielectric metasurface transforms such a BIC into a quasi-BIC (QBIC) with high-quality factor (Q-factor). Typically, the smaller the asymmetry parameter, the larger the Q-factor. However, it is very challenging to fabricate such nanostructures with an ultra-small asymmetry parameter in the experiment due to the limitation of fabrication, thus limiting the measured Q-factor of QBIC. In this work, we demonstrated that BICs can be sustained at Γ-point in an asymmetric dielectric metasurface, where the disturbance parameter of quasi-BIC is accurately controlled in the experiment. The unit cell of the metasurface is composed of a dielectric cuboid with an off-centre hole inside it. Such a BIC can be found by moving the air-hole position in this metasurface. Multipole decompositions and near-field distributions indicate that the toroidal dipole dominates the nature of such a QBIC. Furthermore, we found that such a BIC is robust against the shape of the hole. Besides, two BICs at different wavelengths can be achieved by applying either a rectangular hole or a rectangular lattice. Finally, we presented experimental verifications of BIC types by fabricating asymmetric silicon metasurfaces. Measurement results show that the Q-factor of QBIC can reach almost 5,000. Our results may enrich the library of BICs and find exciting applications in developing high-performance photonics and optoelectronic devices, such as nanolasers, biosensors and enhanced nonlinear harmonic generation.

Item Type: Journal article
Publication Title: Laser and Photonics Reviews
Creators: Zhou, C., Huang, L., Jin, R., Xu, L., Li, G., Rahmani, M., Chen, X., Lu, W. and Miroshnichenko, A.E.
Publisher: Wiley
Date: March 2023
Volume: 17
Number: 3
ISSN: 1863-8880
Rights: This is the peer reviewed version of the following article: Zhou, C., Huang, L., Jin, R., Xu, L., Li, G., Rahmani, M., Chen, X., Lu, W., Miroshnichenko, A. E. (2023). Bound states in the continuum in asymmetric dielectric metasurfaces. Laser and Photonics Reviews, 17(3), 2200564 which has been published in final form at This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.
Divisions: Schools > School of Science and Technology
Record created by: Laura Ward
Date Added: 12 Jan 2024 09:59
Last Modified: 12 Jan 2024 09:59

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