Université Paul Sabatier - Bat. 3R1b4 - 118 route de Narbonne 31062 Toulouse Cedex 09, France

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Surface Quality and Surface Waves on Subwavelength-structured Silver Films

We analyse the physical-chemical surface properties of
single-slit, single-groove subwavelength-structured silver films
with high-resolution transmission electron microscopy (TEM) and
calculate exact solutions to Maxwell’s equations corresponding to
recent far-field interferometry experiments using these
structures. Contrary to a recent suggestion the surface analysis
shows that the silver films are free of detectable contaminants.
The finite-difference-time-domain (FDTD) calculations, in
excellent agreement with experiment, show a rapid fringe amplitude
decrease in the near-zone (slit-groove distance out to 3-4
wavelengths). Extrapolation to slit-groove distances beyond the
near-zone shows that the surface wave evolves to the expected
bound surface plasmon polariton (SPP). Fourier analysis of these
results indicates the presence of a distribution of
transient, evanescent modes around the SPP that dephase and
dissipate as the surface wave evolves from the near to far zone.


Voir en ligne : Phys. Rev. E, 75, 016612 (2007)