Ultrasensitive Higher-Order Exceptional Points via Non-Hermitian Zero-Index Materials
Abstract
Higher-order exceptional points (EPs) in optical structures enable ultra-sensitive responses to perturbations. However, previous investigations on higher-order EPs have predominantly focused on coupled systems, leaving their fundamental physics in open scattering systems largely unexplored. Here, we harness wave interference to realize higher-order EPs in non-Hermitian zero-index materials connected to multiple open channels. Specifically, we show that a three-channel model can give rise to three interesting types of third-order EPs: lasing EP, reflecting EP, and absorbing EP. Notably, near the third-order absorbing EP, we show ultrasensitivity -- a drastic change in output power in response to perturbations at the operating frequency -- in a purely lossy system. These findings pave the way for achieving higher-order and even arbitrary-order EPs in open scattering systems, offering significant potential for advanced sensing applications.
Cite
@article{arxiv.2501.07974,
title = {Ultrasensitive Higher-Order Exceptional Points via Non-Hermitian Zero-Index Materials},
author = {Dongyang Yan and Alexander S. Shalin and Yongxing Wang and Yun Lai and Yadong Xu and Zhi Hong Hang and Fang Cao and Lei Gao and Jie Luo},
journal= {arXiv preprint arXiv:2501.07974},
year = {2025}
}