Transcript Research Poster(zhuo ying wu)

Zhuo Ying Wu
High School for Dual
Language and Asian Studies
Professor Dr. Huizhong Xu
Discussions
Background
Methods
In this work, transmission of light
through a nanoaperture was simulated
by the finite element method using a
commercially available software called
COMSOL Multiphysics [5]. Illumination
was normally incident onto a metal film
through a fused silica substrate on
which the metal film is situated. Inside
the metal film, a nanometer-sized hole
was filled with a dielectric material. The
medium above the metal film is
assumed to be air. A computation
domain of one wavelength in all three
directions is terminated by perfectly
matched layers (PML) which serve as
the PML boundary condition.
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Three-dimensional finite element method
was used to simulate transmission of light
through the dielectric-filled nanoapertures.
Results
Normalized transmission through zincoxide-filled apertures in a 100-nm-thick
silver film is plotted versus aperture
diameter in Fig. 1. Here normalized
transmission T is defined by the ratio of
the transmitted photon flux to the incident
photon flux on the aperture area:
T 
normalized transmission
Transmission of 488 nm light through
zinc-oxide-filled nanoapertures of
various diameters in a silver film was
studied using three-dimensional finite
element method. We found that
transmission displays a resonance peak
at an aperture diameter of around 40
nm. The normalized transmission at this
peak reaches nearly 50% for a film
thickness of 100 nm, and exceeds 100%
for a film thickness of 60 nm. These zincoxide-filled nanoapertures may be useful
for a variety of applications including
optical probe devices with resolution
down to 30 nm.
It can be seen from Fig. 3 that transmission
curves for film thicknesses of 60 nm, 100
nm and 130 nm exhibit a resonance peak
at an aperture diameter around 40 nm. The
peak shifts to smaller aperture diameter
while the normalized transmission at the
resonance increases as the film thickness
decreases.
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Conclusion
50
100
diameter (nm)
150
200
 P dS
n
a 2  I 0
where is the intensity of the incident light,
is the aperture radius, denotes the
component of the time averaged Pointing
vector along the normal to the metal film
plane. The integration is performed over a
circular area of covering the aperture at its
exit.
From Fig. 1, we can see there is a
resonance peak at an aperture diameter of
around 40 nm. The normalized
transmission at this peak reaches 43%.
The electric filed direction inside the
aperture at this resonance is shown
in Fig. 2. The electric field points in the
same direction throughout the whole depth
of the aperture.
Using finite element method, we have
calculated transmission of 488 nm light
through zinc-oxide-filled nanoapertures
with varying diameters in a silver film of
various thicknesses. We found that
transmission displays a resonance
peak at an aperture diameter of ~ 30
nm for a 60-nm-thick silver film and ~
40 nm for a 100-nm-thick film. The
normalized transmission at this peak
exceeds 100% for the 60-nm-thick film.
Acknowledgements
FIG. 2. Field distribution inside aperture
under the same condition described in Fig.
1 for an aperture diameter of 40 nm. False
colors denote the square of the norm of the
electric field (normalized by the incident
electric field) in a logarithmic scale. The
black arrows denote electric field directions.
•Dr. Huizhong Xu
•Dr. Sat
•Harlem Children Society and staffs
•St Johns University and its staffs
• My partner(Samuel Chan)
•Audiences