Robustness of Bound States in the Continuum in Bilayer Structures against Symmetry Breaking
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arXiv
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| Auteurs principaux: | , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866914288083402752 |
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| author | Semushev, Kliment V. Zhao, Zilong Proskurin, Alexey Song, Mingzhao Liu, Xinrui Rybin, Mikhail V. Maslova, Ekaterina E. Bogdanov, Andrey A. |
| author_facet | Semushev, Kliment V. Zhao, Zilong Proskurin, Alexey Song, Mingzhao Liu, Xinrui Rybin, Mikhail V. Maslova, Ekaterina E. Bogdanov, Andrey A. |
| contents | We investigate the robustness of bound states in the continuum (BICs) in a bilayer dielectric rod array against geometric and material perturbations. Our analysis focuses on both symmetry-protected and Fabry-Pérot BICs, examining their transformation into quasi-BICs under three structural modifications: (i) in-plane displacement of one layer, which breaks the C$_2$ symmetry of the system; (ii) introduction of material losses that break time-reversal symmetry; and (iii) variation in the interlayer distance, which preserves structural symmetry. In particular, we demonstrate that material losses inevitably induce radiation in Fabry-Pérot BICs via second-order perturbation processes, converting them into quasi-BICs, while symmetry-protected BICs remain non-radiative. We further show that, despite the inherent instability of BICs under symmetry-breaking effects, their resilience can be significantly enhanced through proper design. Both Fabry-Pérot and symmetry-protected BICs exhibit exponentially weak sensitivity to C$_2$-breaking perturbations as the interlayer distance increases. Finally, we show that additional FP-BICs emerge under oblique incidence, originating from the interference of two high-Q quasi-BICs near the symmetry-protected ones. Our findings pave the way for the development of BIC-based photonic devices with improved robustness against fabrication imperfections, environmental variations, and material losses. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2505_06675 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Robustness of Bound States in the Continuum in Bilayer Structures against Symmetry Breaking Semushev, Kliment V. Zhao, Zilong Proskurin, Alexey Song, Mingzhao Liu, Xinrui Rybin, Mikhail V. Maslova, Ekaterina E. Bogdanov, Andrey A. Optics We investigate the robustness of bound states in the continuum (BICs) in a bilayer dielectric rod array against geometric and material perturbations. Our analysis focuses on both symmetry-protected and Fabry-Pérot BICs, examining their transformation into quasi-BICs under three structural modifications: (i) in-plane displacement of one layer, which breaks the C$_2$ symmetry of the system; (ii) introduction of material losses that break time-reversal symmetry; and (iii) variation in the interlayer distance, which preserves structural symmetry. In particular, we demonstrate that material losses inevitably induce radiation in Fabry-Pérot BICs via second-order perturbation processes, converting them into quasi-BICs, while symmetry-protected BICs remain non-radiative. We further show that, despite the inherent instability of BICs under symmetry-breaking effects, their resilience can be significantly enhanced through proper design. Both Fabry-Pérot and symmetry-protected BICs exhibit exponentially weak sensitivity to C$_2$-breaking perturbations as the interlayer distance increases. Finally, we show that additional FP-BICs emerge under oblique incidence, originating from the interference of two high-Q quasi-BICs near the symmetry-protected ones. Our findings pave the way for the development of BIC-based photonic devices with improved robustness against fabrication imperfections, environmental variations, and material losses. |
| title | Robustness of Bound States in the Continuum in Bilayer Structures against Symmetry Breaking |
| topic | Optics |
| url | https://arxiv.org/abs/2505.06675 |