Photonic Exceptional Topological Bound States in the Continuum
Abstract
Exceptional bound states in the continuum (EBICs) arise when bound states in the continuum (BICs) with distinct intrinsic losses coalesce at exceptional points (EPs), combining continuum-embedded wave confinement with a non-analytic spectral response. However, conventional EBICs rely on precisely controlled modal coupling and intrinsic loss, making them fragile and difficult to realize experimentally. Here, we introduce bulk-band topology to mitigate this fragility and experimentally realize a photonic exceptional topological BIC (ETBIC) in spoof surface plasmon polariton waveguides by merging two symmetry-protected topological BICs (TBICs) to coalesce at an EP, with the topological design supporting robust localization under symmetry-preserving perturbations. By engineering an intrinsic loss contrast and tuning the intermodal coupling, we directly resolve the coalescence of the complex eigenfrequencies, accompanied by measured near-field distributions consistent with the exceptional eigenstate. Furthermore, weak perturbations induce approximately square-root eigenfrequency splitting, yielding an enhanced spectral response compared with the approximately linear frequency shift of an isolated TBIC. These results establish bulk-band topology as a design principle for exceptional BIC engineering and provide a foundation for EBIC-based photonic sensing.
Related
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BibTeX
@misc{chen2026photonic,
title = {{Photonic Exceptional Topological Bound States in the Continuum}},
author = {Liren Chen and Jingming Chen and Zhen Gao},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.08103},
eprint = {2611.08103},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.08103},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Photonic Exceptional Topological Bound States in the Continuum
AU - Liren Chen
AU - Jingming Chen
AU - Zhen Gao
PY - 2026
DA - 2026/11/05
PB - arXiv
DO - 10.48550/arxiv.2611.08103
UR - https://arxiv.org/abs/2611.08103
AB - Exceptional bound states in the continuum (EBICs) arise when bound states in the continuum (BICs) with distinct intrinsic losses coalesce at exceptional points (EPs), combining continuum-embedded wave confinement with a non-analytic spectral response. However, conventional EBICs rely on precisely controlled modal coupling and intrinsic loss, making them fragile and difficult to realize experimentally. Here, we introduce bulk-band topology to mitigate this fragility and experimentally realize a photonic exceptional topological BIC (ETBIC) in spoof surface plasmon polariton waveguides by merging two symmetry-protected topological BICs (TBICs) to coalesce at an EP, with the topological design supporting robust localization under symmetry-preserving perturbations. By engineering an intrinsic loss contrast and tuning the intermodal coupling, we directly resolve the coalescence of the complex eigenfrequencies, accompanied by measured near-field distributions consistent with the exceptional eigenstate. Furthermore, weak perturbations induce approximately square-root eigenfrequency splitting, yielding an enhanced spectral response compared with the approximately linear frequency shift of an isolated TBIC. These results establish bulk-band topology as a design principle for exceptional BIC engineering and provide a foundation for EBIC-based photonic sensing.
ER -