Numerical investigation of energy transport along chains of silver nanorods and nanoplates

摘要

We examine the propagation of energy along chains of silver nanoelements oriented perpendicularly to the flow of light and ordered in several ways. The first chain is composed of vertical silver nanorods arranged in a hexagonal lattice. The second one consists of vertical elongated nanoplates that form a herring-bone pattern. In the third, distribution of vertically oriented nanoplates recalls footsteps. The chains are embedded in a medium with refractive index n = 1 and 1.5. Incident polarized Gaussian beams propagate along chains of nanoelements and have electric field components oriented transversally with respect to the vertical nanoelements. Transport of energy is investigated with the Finite Difference Time Domain (FDTD) method for visible and infrared range of wavelengths, where the Drude model is valid. Propagation constants and attenuation factors are calculated. Losses are due to absorption in metal and light scattering on structure elements. In the analyzed structures, energy is transported due to localized surface plasmons-polaritons, where the amplitude of optical fields is locally enhanced by orders of magnitude. This property might be useful in the construction of nanoscale photonic devices. The smaller the metallic elements are, the stronger is the concentration of energy. Waveguides of that form may be used for creating a medium with novel effective electromagnetic properties.