Periodic arrays are an exceptionally interesting arrangement for plasmonic nanostructures due to their ability to support strong collective lattice resonances, which arise from the coherent multiple scattering enabled by the array periodicity. Thanks to these exceptional properties, periodic arrays are being exploited in a wide variety of applications, including ultrasensitive biosensing, nanoscale light emission, and color printing, to cite a few.

The goal of this seminar is to provide an instructive introduction to this topic. To that end, we will start by discussing how the interplay between the response of the individual constituents of the array and their collective interaction determines the ultimate limits of the field enhancement provided by a periodic array. We will also discuss the response of arrays with multi-particle unit cells using an analytical approach based on plasmon hybridization, which provides a simple and efficient way to design periodic arrays with engineered properties. We will pay particular attention to bipartite arrays and show how, depending on the relative position of the particles within the  unit cell, these systems can support super- or subradiant lattice resonances with very different optical responses.

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