Download Prof. Eli Yablonovitch, UCLA

Plasmonic Imaging for Optical
Lithography
X-ray Wavelengths at Optical Frequencies
Experiments: Progress and Plans
Yunping Yang
Josh Conway
Eli Yablonovitch
The Problem
Classically the resolution limit is determined by the Rayleigh Criterion:
Sin  

d
Various schemes have been developed to push this to finer resolution than
the wavelength itself, but the scale will always be set by wavelength
Constant Energy Curves
By adiabatically tapering the thin film thickness,
very small (<50nm) plasmon wavelengths are
attainable for in plane imaging.
Plasmon Wavelength in nm
p
Silver Film on Sapphire
1.5 eV
400
400
300
300
2.0 eV
200
200
100
100
2.5 eV
Ag
Air
Sap p hire
0
100
80
60
40
20
0
0
0
0
20
20
40
40
60
60
1
2
3
80
80
Silver Film Thickness in nm
4
5
100
t
Dispersion Relation: Constant Thickness Curves
Plasmon Wavelength in nm
h
4
200 100 50 40 30
4
10
Sap p hire
3.5
t=5nm
3
t=20nm
t=2nm
2.5
t=1nm
2
w(eV)
Plasmon Energy in eV
15
Air
Ag
3
20
t=thickness of metal film
2
1.5
1
1
Optical frequencies,
but with X-ray wavelengths!
0.5
0
0
0
0
0.02
0.04
0.06
0.08
0.1
0.1
0.12
0.14
0.16
0.18
0.2
0.22
0.2
0.24
0.26
0.28
0.3
Wavenumber
0.32 (rad/nm)
0.3
0.34
0.36
0.38
0.4
0.4
0.42
0.44
0.46
0.48
0.5
0.52
0.54
0.56
0.5
Plasmon Wave-Vector (2/wavelength in nm)
0.58
0.6
0.6
0.62
0.64
k
Grating Coupler
Grating
Silver
Glass
• Design and
fabricate
gratings to
maximize the
coupling
efficiency;
• Verify the DR
with constant
thickness;
• Find some
material
parameters
Launching of Surface Plasmons: ATR Coupler
Optical Setup for ATR Coupler
Iris
PBS
Mirror
Laser
/2
Beam
Expander
Lens
Sapphire
Hemisphere
Detector
4f
Lens
Lens
Lens
4f
Ag Thin Film
Optical Setup for ATR Coupler
• Characterize thin film, such as
roughness, thickness;
• Experimentally verify the dispersion
relation;
• Launching a standing wave for
Plasmon Wavelength Measurement
A Possible Solution
This permits X-ray wavelengths at optical frequencies
Plasmon Wavelength Measurement
Resolution: 1.6 nm
Antonello Nesci, Rene Dandliker, Hans Peter Herzig, “Quantitative amplitude and phase measurement by
use of a heterodyne scanning near-field optical microscope,” Optics Letters, Volume 26, Issue 4, 208-210.
Taper Motivation
n9> n8>       >n1>n0
Taper design will
n
far-field from
n
be a trade
n
n
n
conventional
lens
n
between
n
n
n
absorption (joule
n
heating),
scattering (an
taper
adiabatic
profile), and
maintaining a
dimple lens
high enough
effective index at
out-coupling
0
1
2
3
4
5
6
7
8
9
Criteria
0.4
Thus we
change are
adiabatic
criteria
0.3
Loss/
It is clear that
Loss/
becomes
prohibitively
large at short
wavelengths
0.2
0.1
0.0
0
50
100
Wavelength (nm)
150
Silver Film Thickness (nm)
Taper Profile
70
250
60
60
200
50
50
150
100
40
40
50
30
30
0
0
100
200
300
400
500
600
700
20
20
10
10
0
0
100
100
200
200
300
400
300
400
Length (nm)
500
500
600
600
700