Disorder in optical metamaterials made of silver nanospirals

We report on a numerical study of the optical properties of silver square nanospirals. The resonant modes of the nanospirals presented current distributions similar to those of U-shaped resonators. The resonance frequencies of the ‘electric’ modes were relatively insensitive to coupling, except for the shortest distance, whereas for the ‘magnetic’ modes they steadily increased with coupling. Aperiodicity in the strong coupling regime did not modify the strength and resonance frequency of all modes as compared to the case of periodic arrays.