2D plasmonic gold nano-patches for linear and nonlinear applications

•Different plasmonic resonances can be excited in 2D gold square nanopatch arrays.•The fabricated devices are insensitive to light polarization.•A plasmonic biosensor with a sensitivity and a figure of merit of 630 nm/RIU and 21, respectively, is presented.•Color variation is a quick tool to predict refractive index changes.•The 2D gold nanopatch arrays can be exploited for Surface Enhanced Raman Scattering with an enhancement factor up to 2 × 105.

We demonstrate the fabrication of a 2D periodic arrangement of gold square nano-patches on both silicon and borosilicate glass substrates whose optical properties can be exploited for both linear and nonlinear applications. The comparison between numerical and experimental results, combined with high-resolution scanning electron microscopy images highlights the importance of the geometry and the fine shape in the determination of the square gold nano-patches optical properties.

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