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Optical resonances in bipartite metal nanostructure lattices are more resilient to finite size-effects than equivalent unipartite lattices, but the complexities of their behaviour in non-ideal settings remain relatively unexplored. Here we investigate the quality factor and extinction efficiency of 1D Ag and Au unipartite and bipartite lattices. By modelling finite size lattices over a range of periods we show that the quality factor of Ag bipartite lattices is significantly better than unipartite lattices. This improvement is less pronounced for Au bipartite lattices. We also show that bipartite lattices are dramatically affected by structure size variations at scales that are typically seen in electron beam lithography fabrication in contrast to unipartite lattices, which are not as sensitive.

In this paper we explore how nano-structure arrays can help improve plasmonic sensors and imaging devices. By using a periodic array the range of parameters that can be varied to give a specific response increases dramatically compared to devices based on individual structures. We show that plasmonic arrays can be engineered to show high quality spectral extinction peaks controlled primarily by the angle of incidence and period with minimal dependence on the structure. This gives flexibility in designing plasmonic sensing or imaging devices. The fabrication of the nanostructure arrays is presented as well as optical verification of the localised plasmon resonance response. Spectral simulation results are also obtained for the arrays using Scattering by Multiple Particles in Thin Film Systems (SMUTHI) software which proves to be a useful tool in analysing the response of plasmonic arrays.

Subradiant surface lattice resonances are of interest due to their remarkably high quality factors. In this work, these high quality resonances are experimentally investigated in the visible spectrum with Au and Ag bipartite disk lattices fabricated with electron beam lithography. Subradiant resonances are also compared to unipartite surface lattice resonance with angle-resolved extinction measurements, which are supported by numerical models. Finally, the lattice parameters are optimized to show high quality factors in lattices where the elements have a diameter difference as small as 10 nm.