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arXiv · 2606.06998

Arbitrary-Order Scattering Exceptional Points in Configurable Non-Hermitian Zero-Index Materials

Yucheng Xu·Ling Yin·Yongxing Wang·Jie Luo
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Abstract

Scattering exceptional points (EPs) are non-Hermitian degeneracies where the eigenvalues and eigenvectors of scattering matrices coalesce, enabling many intriguing phenomena in optical systems. Higher-order scattering EPs are particularly notable for their ultrasensitive response to perturbations, yet achieving flexible, arbitrary-order control remains challenging. Here, we propose a configurable non-Hermitian zero-index material (ZIM) network that enables arbitrary-order scattering EPs, as rigorously proved theoretically and validated numerically. Specifically, we show that in an N-port non-Hermitian ZIM network embedded with loss/gain dopants, the maximum achievable EP order is N, and the order can be flexibly tuned from 2 to N or completely eliminated by adjusting the dopants. Furthermore, we compare conventional coherent perfect absorption with absorbing EPs of different orders. Although both achieve perfect absorption of all incident waves, a second-order EP already outperforms coherent perfect absorption, and higher-order EPs provide further power-law enhancement. These findings establish a pathway toward realizing arbitrary-order EPs in open scattering systems, holding significant promise for advanced sensing applications.

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Yucheng Xu, Ling Yin, Yongxing Wang, Jie Luo. 2026-06-05. Arbitrary-Order Scattering Exceptional Points in Configurable Non-Hermitian Zero-Index Materials. https://doi.org/10.1021/acsphotonics.6c00842

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