Resonance of surface-localized plasmons in a system of periodically arranged gold and silver nanowires on a dielectric substrate

Abstract

The plasmon resonance of nanogratings consisted of periodically arranged square cross-section nanowires of a copper and aluminum on the dielectric substrate was studied by the rigorous coupled-wave analysis. The cross-sections of the nanowires are 30 × 30 nm2 and 50 × 50 nm2. The period was equal to 0.06 μm and 0.1 μm. The spectral dependences of the absorption, reflection and transmission coefficients of the nanograting in the wavelengths range from 0.1 to 1.0 μm were calculated. The field distribution at the interfaces of grating-air and grating-substrate was simulated. The maximum absorption is calculated at the wavelengths of 0.555 μm for copper and wide absorption band from 0.12 to 0.22 μm for aluminum gratings. The resonance peak for aluminum nanowires splits into two or more peaks. Spectral characteristics of the copper nanowires are similar to the corresponding characteristics of the gold nanowires; however, the maximum absorption is shifted to the long-wave region from 0.525 μm for gold nanowires to 0.555 μm for copper. It is necessary to use more number of coupled waves for the aluminum grating than for copper. That is from the point of view of the calculation convergence. Therefore, the electromagnetic fields at the resonance wavelengths which occur in the aluminum nanowires are stronger than in comparison to the copper nanowires.