Proceedings of Topical Meeting on Optoinformatics (pdf-format, 1.21 ...

SAINT-PETERSBURG, October 17 – 20, 2005 55
First setup
Incident E perpendicular to line that connects centers <strong>of</strong> holes
2.6
two holes
2.4
three holes
Second
Figure 2 shows some results for two
setups: in the first we have two
identical holes and in the second we
have three identical holes, both with
their centers aligned. The holes are
cubic: L x = L y = D = λ/4, with λ the
wavelength <strong>of</strong> the incident light. The
distance between the centers <strong>of</strong> the
holes is varied. We show the energy
flux through one hole (the center
hole for the second case), normalised
by the energy flux through an
identical, solitary hole. Note that this
energy need not reach the far field, it
may scatter into evanescent
contributions below the layer. In the
top figure, the incident field is a
perpendicular incident, S-polarised
plane wave. In the lower figure, the
incident field is P-polarised.
Enhancement <strong>of</strong> the energy flux
occurs only for holes that are very
near for the S-polarised incident
field, whereas for P-polarisation,
both enhancement and attenuation
occur for larger distances between
0.8
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
distance (units <strong>of</strong> wavelengths) between centers <strong>of</strong> holes
Fig. 2. Normalised energy flux through a hole as a function
<strong>of</strong> distance between the holes. Solid line for the case <strong>of</strong>
two identical holes, dotted line for three identical holes.
the holes. This points to the contribution <strong>of</strong> plasmon effects in the latter case, whereas for
S-polarisation enhancement is mainly due to evanescent fields.
This research was supported by the Dutch Technology Foundation STW.
normalized energy flux
normalized energy flux
2.2
1.8
1.6
1.4
1.2
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2
1
1.6
1.4
1.2
1
0.8
0.6
0.4
Incident E parallel to line that connects centers <strong>of</strong> holes
two holes
three holes
0.2
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
distance (units <strong>of</strong> wavelengths) between centers <strong>of</strong> holes