Microwave Plasmonic Exceptional Points for Enhanced Sensing

Abstract

AbstractThe emergence of exceptional points in a non‐Hermitian system has provided intriguing possibilities to enhance the sensitivity of a sensor, while it is yet a considerable challenge to implement subwavelength non‐Hermitian systems. One possible solution to tackle this challenge is to take advantage of localized surface plasmon resonances, which enable large electromagnetic enhancement at the subwavelength scale. In this work, a novel sensing scheme based on the exceptional points in a spoof plasmonic structure working at microwave frequencies is proposed. It is shown that near‐field plasmonic vortices can be efficiently generated at the exceptional points, resulting in the enhanced sensitivity when detecting a single particle or fluid analytes. Single particle detection with the particle size as small as 1/100 of the operating wavelength is reported. For liquid analysis in the microfluidic system, the sample consumption is down to 0.72 μL. This work demonstrates the ultrahigh sensitivity of exceptional‐point‐based plasmonic sensing and opens up new possibilities for subwavelength and compact sensors operating in the microwave, terahertz, and even far‐infrared regions.