Design of broadband metal nanosphere antenna arrays with a hybrid evolutionary algorithm.

This Letter presents a method for the design of metal nanosphere antenna arrays with broadband plasmonic field enhancement over the whole visible spectra. In particular, thanks to a customized hybrid genetic algorithm (HGA), the plasmonic near-field enhancement and the sidelobe level are maximized and minimized, respectively, by thinning the nanoarray, optimizing the elements spacing and dimensions. In particular the problem is recast as an optimization one by defining a suitable cost function, which is then minimized with the HGA. The obtained preliminary results demonstrate the potentialities of the proposed approach.