Highly Sensitive and Topologically Robust Multimode Sensing on Spoof Plasmonic Skyrmions

Abstract Recent concept of spoof plasmonic skyrmions has attracted much attention for their topologically robust and multiple equidistance sharp resonances. However, highly‐efficient excitation and its implementations for broadband sensing still remain elusive. Traditional resonant measurements for characterizing dielectric materials in a closed metal cavity are accurate, but are often limited to narrow band of frequencies. Additionally, samples must be carefully prepared and precisely placed in the cavity. In this paper, a topologically robust and ultracompact sensor based on spoof plasmonic skyrmions is developed for characterizing dielectric materials in a wideband with ultrahigh sensitivity. By simply feeding a coaxial probe vertically to the surface center of the skyrmions structure, topologically robust multimode plasmonic skyrmions resonance spectra can be excited and captured with high efficiency. Simulation and experimental results of three skyrmions sensors in different shapes (circle, square, and hexagon) with equal effective length demonstrate that spoof plasmonic skyrmions sensor features are highly sensitive (>4.82%) and extremely accurate (≈99.99%) sensing performance against continuous shape deformations. These results open up an avenue for multiple resonant measurements of dielectric materials in broadband and provide a very versatile platform for the design and fabrication of ultracompact and topologically robust plasmonic sensors.