High-order exceptional point based optical sensor

Exceptional points (EPs) could potentially enhance the sensitivity of an optical sensing system by orders of magnitude. Higher-order EP systems, having more complex physics, can further boost this parameter. In this paper, we investigate the response order of high-order non-Hermitian systems and provide a guideline for designing a sensor with high response order. Based on this design rule, we propose and demonstrate an optical sensor with a fourth-order response, and analyze its associated properties. The four resonant wavelengths of our optical sensor simultaneously collapse at a high-order exceptional point in the parameter space, providing a fourth root relation between the amount of wavelength splitting and the amplitude of the perturbation. A large sensitivity enhancement factor over 100, is observed when the wavelength splitting is compared with traditional single resonator-based sensors under small perturbation conditions. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

This paper investigates the response order of high-order non-Hermitian systems, provides guidelines for designing a sensor with high response order, and demonstrates an optical sensor with a fourth-order response. The sensor shows a large sensitivity enhancement factor over 100 compared to traditional single resonator-based sensors under small perturbation conditions.