Nanoripple patterns with long-range order have been fabricated on amorphous dielectric films by Xe + ion etching. They are used as templates to elaborate organized arrays of aligned Ag nanoparticles by grazing incidence ion-beam sputtering. The particles present an ellipsoidal shape with a major axis parallel to the ripples. Optical calculations show that both the spatial organization and shape anisotropies contribute to a strong dependence of the surface-plasmon resonance of the nanocomposite films on the orientation of the electric field.

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