Surface lattice resonances for high-performance sensing: a study on gold nanoparticle arrays.

In this study, localized surface plasmon resonances and diffractive coupling effects in periodic arrays of gold nanoparticles, which give rise to surface lattice resonances, were systematically explored. Using the finite element method simulations in COMSOL Multiphysics, we analyzed how nanoparticle geometry and lattice configuration affected the quality factor and sensitivity. Compared to isolated nanoparticles, periodic arrays of nanospheres, nanodisks, and nanorods exhibited significantly enhanced sensing capabilities due to diffractive coupling, achieving quality factors an order of magnitude higher and bulk sensitivity improvements exceeding 100 nm/RIU. This article confirms experimentally the emergence of hybrid spectral features in such periodic arrays, resulting in narrower resonances and enhanced sensing performance. A proof-of-concept sensor based on a 600-nm periodic gold nanodisk array demonstrates reliable sensitivity, validating that even simple geometries can achieve high performance by harnessing the collective effects of periodicity. These findings emphasize the strong potential of gold nanoparticle arrays in high-performance sensing applications empowered by surface lattice resonances.