Impact of intra- and inter-unit cell symmetry breaking on the optical response of the arrays of nanotrimers.

Abstract

Understanding the impact of geometric changes on the properties of otherwise symmetric nanostructures is of essential importance for nanophotonics. In this Letter, we show that intra- and inter-unit cell symmetry breaking can substantially modify the optical properties of nanotrimers from both the experimental and simulation aspect. Specifically, shifting the location of one nano-dot within the trimer unit cell leads to the formation of magnetic Fano resonances with loop-like polarization patterns that are not present in the symmetric configuration. We further unlock the impact of lattice modification on the optical response of square arrays of trimers with broken three-fold rotation symmetry and with intra-trimer distances as small as 25nm, showing distinctively different spectral evolutions of the electric and magnetic Fano resonances. The results achieved highlight the symmetry breaking as an essential tool to unlock and strengthen predefined resonances, which can have important applications, particularly in the field of sensing.