Very large plasmon band shift in strongly coupled metal nanoparticle chain arrays.

MeV silicon ion irradiation of silica glass containing 10 nm silver nanocrystals causes alignment of the nanocrystals in closely spaced linear arrays along the ion tracks. Optical transmission measurements show a 1.5 eV splitting of the surface plasmon resonant absorption bands for polarizations longitudinal and transversal to the arrays. The resulting material is a highly anisotropic glass that absorbs blue light of one polarization, and near-infrared light of the orthogonal polarization. Finite-difference time domain simulations are used to explore the effects of interparticle spacing and total array length on the absorption properties.