Abstract
We have studied numerically the diffraction of a surface plasmon polariton (SPP) when it encounters a wide multi-wavelength slit in conducting films. As a jump process a SPP is excited beyond the slit by wave scattering at the second slit edge. The exciting radiation is produced when the incident SPP collapses at the first slit edge. We have found that the transmitted SPP supports inherent and unavoidable interference with grazing scattered radiation; the spatial modulation extends to the fields in the diffraction region where a series of low intensity spots arises. We demonstrate that the SPP generated on the second slab depends on the frequency but not on the wave vector of the collapsed SPP; a SPP is transmitted even when the two metals forming the slit are different. The numerical results were obtained using the Finite Difference Time Domain (FDTD) method with a grid size λ/100.
Highlights
Surface plasmons (SPs) are vibrational normal modes of free electrons at the surface of conducting media
We have studied numerically the diffraction of a surface plasmon polariton (SPP) when it encounters a wide multi-wavelength slit in conducting films
As a jump process a SPP is excited beyond the slit by wave scattering at the second slit edge
Summary
Surface plasmons (SPs) are vibrational normal modes of free electrons at the surface of conducting media. In order to gain insight into the mechanisms involved in the SPP jumping, we study separately a) the radiation emitted by a diffracted SPP that collapses in a rectangular border, and b) the light scattering by a metallic 90◦- corner when the wave vector of an incident plane wave is parallel to one of the two surfaces forming the corner. These two physical processes are the starting point for describing the SPP transmission through wide slits. This face-fire technique can be used to fabricate nanostructures by SPP interference nanolithography[31] and to study new wave phenomena by conical edge diffraction.[32]
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