Study on high-Q supercavity mode in spoof localized surface plasmon structures

Abstract

We report experimentally high-Q resonances arising from quasi-bound states in the continuum (quasi-BICs), supported by spoof localized surface plasmon (SLSP) structures with broken symmetry. The influence of structural asymmetric parameters on the Q-factors of SLSP resonance is studied with numerical simulations and experiments, and the supercavity mode with small spectral width is observed as the central displacement of the SLSP structure is approaching zero. Our investigation has demonstrated a new mechanism in suppressing the radiation loss of SLSP structures, holding promise for sensing applications with high sensitivity.