Exceptional-Point Sensor Based on Spoof Localized Surface Plasmons

In this work, an exceptional point (EP) sensor based on spoof localized surface plasmons (SLSPs) is developed for characterizing deep-subwavelength single particles. Through feeding a microstrip line adjacent to a suspended SLSPs resonator, multimode plasmonic resonance spectra can be efficiently excited and captured. We implement an EP state at the tetradecapolar mode by precisely manipulating the positions of two movable Rayleigh scatterers. This sensor not only features remarkable sensitivity enhancement, but shows its superiority in detecting deep-subwavelength targets with a minimum dimension of 0.001λ (λ is the wavelength of the tetradecapolar mode). This novel scheme provide a comprehensive platform for the design of EP-based sensors in spoof localized surface plasmons systems.