We present a numerical study of the interaction of light with isolated nanoparticles of various symmetry shapes described by the Gielis superformula as well as nanoparticle arrays composed from them. Using the discrete dipole approximation and finite element numerical methods the effects of particle shape symmetry on the spectral properties of gold and silver nanoparticles were investigated. Starting from the spherical and cylindrical geometries and progressing to star-like polygonal shapes, we demonstrate that the variation of the symmetry can significantly enhance the strength of the dipolar resonance and shift the resonance to the red spectral range by hundreds of nanometres. Thus, is possible to tune the optical properties of the nanostructures all across the visible spectral range only by changing their shapes. Finally, we investigate the collective resonances of arrays of interacting nanoparticles of different shapes, elucidating the role of the particle symmetry in the collective response.

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R. Margoth Cordova Castro, Alexey V. Krasavin, Wayne Dickson, Eugenio R. Mendez Mendez, and Anatoly V. Zayats, "Shape matters: tuning plasmonic resonances into single nanoparticles and their arrays (Conference Presentation)," Proc. SPIE 9921, Plasmonics: Design, Materials, Fabrication, Characterization, and Applications XIV, 99211R (Presented at SPIE Nanoscience + Engineering: September 01, 2016; Published: 9 November 2016); https://doi.org/10.1117/12.2237361.5161456667001.