Realizing the diffraction coupling of silver nanodisk pair array for high-quality sensing

Abstract

We report a novel approach to enhance the local electromagnetic fields of silver nanodisk pair arrays to achieve high-quality sensing. It is found that through lifting metallic nanodisk pair array by dielectric nanopillars to decrease the effects of substrates, the strong diffraction coupling of metallic nanodisk pair array can be achieved, which will result in a mixed localized surface plasmon resonance (LSPR) with huge electric field enhancement. More importantly, we also demonstrate that for such a diffraction coupling, the electric field component of the lattice resonance mode of periodic arrays must be parallel to the induced electric moment in the silver nanodisk pair array. Due to ultra-narrow linewidth and great electric field enhancement at the LSPR, the metallic nanodisk pair array performs high sensitivity (S = 760 nm RIU−1, S* = 89.5 RIU−1) and figure of merit (FOM = 492, FOM* = 6147), which holds important applications in high-efficiency biomedical sensing.

Keywords

• Plasmonics
• Ultra-narrow linewidth
• Optical sensing and sensors
• Lifted nanoantenna arrays