Supporting Information
Zheng et al. 10.1073/pnas.0912563107
SI Text
Fig. S1
A
shows the optical transmission images of the 9
linear-groove-based surface-wave-enabled darkfield apertures
(SWEDA) and the reference single-hole at normal-incidence
transverse-magnetic (TM) illumination for three different wave-
lengths. We can see that the spacing parameter
“
s
”
does indeed
have a significant impact on the TM transmission of these struc-
tures. The TM transmission intensity measured for these linear-
groove-based SWEDAs with different spacing
s
are plotted in
Fig. S1
B
(wavelength of 750 nm); we used the transmission of
the unadorned simple hole for normalization. The simulation
prediction for each of the structures is also plotted for compar-
ison. From the plots, we can see that the implemented linear-
groove-based SWEDA structure with s-parameter of 655 nm ex-
hibited the desired near-zero transmission characteristics. The
optimal structure parameters were a close match with our simu-
lation predictions
—
the
s
parameter differed by 3 nm (<
0
.
5%
).
The measured darkfield suppression factor for the optimized
linear-groove-based SWEDA was 5080. In other words, this struc-
ture transmitted 5080 times less TM light than an unadorned sim-
ple hole of size equal to that of the central SWEDA hole. We next
measured the spectral transmission response of the optimized lin-
ear-groove-based SWEDA over a spectral range of 700 nm to
800 nm. Because operation of the linear-groove-based SWEDA
depends on the exact balance and opposing phase relationship of
the surface-wave-enabled transmission component and the direct
transmission component, we can expect that the TM darkfield
property of linear-groove-based SWEDA to be optimized for only
a single wavelength. Fig. S1
C
shows the experimentally measured
and simulation-predicted spectral transmission. As expected,
there is a single minimum over the range of interest and the trans-
mission increases monotonically away from this point. It is also
worth noting that the suppression factor actually remained fairly
high (
>
50
) for a bandwidth of approximately 10 nm.
Spacing
‘
s
’
(nm)
λ
λ
=720nm
λ
=750nm
λ
=780nm
Single hole
No transmission
455
495
535
575
655
615
735
695
775
AB
450 500 550 600 650 700 750 800
1E-5
1E-4
1E-3
0.01
0.1
1
10
Normalized intensity
Spacing
'
s
'
(nm)
Simulation
Experiment
700
720
740
760
780
800
1E-5
1E-4
1E-3
0.01
0.1
1
Normalized intensity
Incident wavelength (nm)
Simulation
Experiment
C
Fig. S1.
(
A
) The optical transmission images of the 9 SWEDAs and the reference single-hole under normal-incidence illumination for three different wave-
lengths. (
B
) The measured optical transmission signals from SWEDAs with different spacing
s
ranging from 455
–
775 nm (left to right). The signals from the
SWEDA were normalized by single hole (signal from the single hole at normal incidence was set to unity). The measured suppression factor for the optimi
zed
SWEDA is 5080. The simulated intensity is also shown for comparison. (
C
) The measured normalized optical transmission signals from SWEDA (
s
¼
655
nm) with
different incident wavelengths. The simulation result is also shown for comparison. In this set of simulations, the permittivity values for gold at d
ifferent
wavelengths given in ref. 1 were used.
1. Palik E, Ghosh G (1985)
Handbook of Optical Constants of Solids
(Academic, New York).
Zheng et al.
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