Detailed formation mechanism of sharp plasmonic lattice modes on Au hemi-ellipsoid arrays in inhomogeneous environment

Abstract

Plasmonic lattice modes on the periodic arrays of Au hemi-ellipsoids on quartz substrates (inhomogeneous environment) is demonstrated experimentally. It is found that formation of plasmonic lattice modes results from the coupling between the resonance of Au hemi-ellipsoids and the diffracted waves inside the substrates. The quality factor of plasmonic lattice modes can be attributed to three factors: the weakening of zero-order diffracted waves, the strengthening of hemi-ellipsoid’s resonance and the match between the period of the arrays and nanoparticles’ resonance wavelength. Experiments show that the backward incidence results in a sharper transmission valley than the forward incidence.