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The tunneling of surface plasmon-polaritons (SPPs) across an
interruption in the metallic film supporting them is numerically investigated
in details. Both non-symmetrical and symmetrical geometries are
considered. A very high tunneling efficiency is calculated for the long-range
surface plasmon in the symmetrical geometry, with an amplitude
transmission as high as 80% over a 5 μm gap for a 40 nm thick gold film
illuminated at λ=785 nm. The transmission is somewhat lower in the nonsymmetrical
geometry. The coupling between the different SPP modes
(radiative and non-radiative) in that geometry is also investigated in detail.
This coupling depends periodically upon the length of the gap. Overall, the
results indicate that SPPs are not very sensitive to technological
imperfections and can survive large waveguide interruptions.
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