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Transmission of Light through Dielectric-Filled Nanoapertures. By: Samuel Chan Zhuo Ying Wu. Mentor: Dr. Xu. St. John’s University, August, 2009. Outline. Motivation. Introduction to Dielectric-filled Nanoapertures. Previous Results. Current Work. Conclusion. - PowerPoint PPT Presentation
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Transmission of Light through Dielectric-Filled Nanoapertures
By: Samuel Chan Zhuo Ying Wu
St. John’s University, August, 2009
Mentor: Dr. Xu
• Motivation
• Introduction to Dielectric-filled Nanoapertures
• Previous Results
• Current Work
• Conclusion
Motivation: The Diffraction Limit
a. The Image of a Point Source
b. The Illumination Profile
• Point spread Function (PSF) depends on numerical aperture and wavelength. • Typical PSF (NA~1, 780 nm):1 micron by 0.5 microns.
Motivation: Break the Diffraction Limit
Resolution ~ ..
61.0
Metal-coated fiber
R. C. Dunn, Chem. Rev. 99, 2891 (1999).
resolution: /5
Objective lens
Focal volume
Excitation volume
Metal tip
Laser illumination
E. J. Sanchez et al., Phys. Rev. Lett. 82, 4014 (1999).
resolution: /10
N. Fang et al., Science 308, 534-537 (2005).
resolution: /4
Schematic of Light Transmission through an Aperture
Metal
Substrate
Illumination
simulation
3-D finite element methodwith perfectly matched layer B.C.
A finite element method (FEM) software package for various physics and engineering applications, especially coupled phenomena, or multiphysics.
COMSOL Multiphysics RF Module
Previous Results: Resonant Transmission
Au
Fused Silica
Illumination
a-Si Film thickness: 200 nm = 810 nm
ph
ase
shif
tFabry-Perot Interferometer
Fabry-Perot Resonances inside Waveguide
phase shift = 2 phase shift = 420
0 n
m
55 nm 105 nm
Black arrows: electric field directions-5 -4 -3 -2 -1 0 1 2
)||/|log(| 20
2 EE
H. Xu et al., Opt. Commun. 282, 1467-1471 (2009).
Current Work: Transmission through ZnO-filled nanoapertures in silver
Ag
Fused Silica
Illumination
ZnO Film thickness: 100 nm = 488 nm
Previous work:
silicon-filled aperture in gold
nSi: 3.882-0.099*inAu: 0.157-4.991*i
Current work:
ZnO-filled aperture in silver
nZnO: 2.06nAg: 0.131-2.81*i
Transmission through ZnO-filled nanoapertures in silver
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
0 20 40 60 80 100 120 140 160 180 200Diameter (nm)
Nor
mal
ized
Tra
nsm
issi
on
Hole depth: 200 nm
Phase = 0
Transmission through ZnO-filled nanoapertures in silver with various thickness
0.00
0.50
1.00
1.50
2.00
2.50
3.00
0 20 40 60 80 100 120 140 160 180 200
60nm
100nm
130nm
160nm
Diameter (nm)
Nor
mal
ized
Tra
nsm
issi
on
Application: Nanoscopic Near-field Probe
30 nm
Aluminumcoating
Si
SiO2
Illumination at 488 nm
-4 -3 -2 -1 0 1
)||/|log(| 20
2 EE
core
metal
tapered fiber
Enhancement in near-field intensity ~1000 times by silicon filling!
Conclusion
• Transmission resonance peaks were found at aperture diameter of around 40 nm for ZnO-filled nanoapertures with normalized transmission of ~ 100%.
•ZnO-filled nanoapertures may be useful for optical scanning probe devices that yield resolution of less than /10.
AcknowledgementsDr. Huizhong Xu
St. John’s University and staff
Dr. Sat Bhattacharya
Harlem Children Society
All of you!!