Incomplete plasmonic hybridization induced broadband band-stop filtering in metasurface

Surface plasmon hybridization improves the physical properties of the plasmonic modes and opens up new possibilities for light manipulation at the nanoscale. In this paper, we investigated the broadband band-stop filtering characteristics of a metasurface composed of two metal nanocube arrays separated by a dielectric film. The filtering bandwidth of over 100 nm in the visible region was demonstrated, with a transmittance of less than 0.5 % across the whole filtering range. The incomplete plasmonic hybridization model was proposed, which accurately describes the broadband spectral response. In contrast to full hybridization, incomplete hybrid modes can contain varying percentage admixtures of the primitive modes, allowing incident light in a broadband range to meet the momentum-matching condition. The analysis of the dependence of the reflection, absorption, and transmission spectra on the structural parameters further validates the results. The proposed broadband filter was experimentally validated and found to be in good agreement with numerical results. Our in-depth analysis of the hybrid coupling mechanism opens up a new avenue for designing broadband optical devices.