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Optical Antennas for Optical Antennas for Raman SpectroscopyRaman Spectroscopy
Laura MatloffMentor: Matteo Staffaroni (EECS)
Faculty Sponsor: Prof. Yablonovitch
At AirportsAt Airports
Compact desktop explosives/narcotics detection system
Sample collection swab
Security Guy
Your check-in luggage
nose
Pump Photon
Target Molecule in Ground State
Excited State
Pump Photon
Ground State
Virtual Level
Raman Spectroscopy
Pump Photon
Target Molecule in Excited State
Pump Photon
Virtual Level
Ground State
Excited State
Stokes-shifted Photon
Stokes-shiftedPhoton
Raman Spectroscopy
Phot
on C
ount
s
Wavelength (nm)
514 524 524 534 544 554504
Pump Photons
The likelihood of a Raman scattering event depends on the intensity of the light in the neighborhood of the molecule
Phot
on C
ount
s
Wavelength (nm)
514 524 524 534 544 554504
Pump Photons
Stokes-shifted Photons
For single molecule detection (E-Field enhancement)4 > 1014
2
1.64
The Dipole AntennaThe Dipole Antenna
Antenna Arm Length (µm)
0 2L =7 ( m), Gold Antenna
Antenna Arm Length (µm)
0 2L =7 ( m), Gold Antenna
Antenna Arm Length (µm)
0 2L =7 ( m), Gold Antenna
Antenna Arm Length (µm)
0 2L =7 ( m), Gold Antenna
Antenna Arm Length (µm)
0 2L =7 ( m), Gold Antenna
Antenna Arm Length (µm)
0 2L =7 ( m), Gold Antenna
Antenna Arm Length (µm)
0 2L =7 ( m), Gold Antenna
Antenna Arm Length (µm)
0 2L =7 ( m), Gold Antenna
Antenna Arm Length (µm)
0 2L =7 ( m), Gold Antenna
Antenna Arm Length (µm)
0 2L =7 ( m), Gold Antenna
Antenna Arm Length (µm)
0 2L =7 ( m), Gold Antenna
Antenna Arm Length (µm)
0 2L =7 ( m), Gold Antenna
Antenna Arm Length (µm)
0 2L =7 ( m), Gold Antenna
Antenna Arm Length (µm)
0 2L =7 ( m), Gold Antenna
Antenna Arm Length (µm)
0 2L =7 ( m), Gold Antenna
Antenna Arm Length (µm)
0 2L =7 ( m), Gold Antenna
Single molecule detection requires electric field enhancement of 1014
1016
1014
1012
1010
108
106
104
102
1
OpticalAntenna Antenna Arm Length (µm)
=830 (nm), Gold Antenna
Single molecule detection requires electric field enhancement of 1014
1016
1014
1012
1010
108
106
104
102
1
OpticalAntenna
Single molecule detection requires electric field enhancement of 1014
1016
1014
1012
1010
108
106
104
102
1
OpticalAntenna
Single molecule detection requires electric field enhancement of 1014
1016
1014
1012
1010
108
106
104
102
1
OpticalAntenna
Single molecule detection requires electric field enhancement of 1014
1016
1014
1012
1010
108
106
104
102
1
OpticalAntenna
Grating Coupler
Grating CouplerGrating Coupler
COMSOL ModelCOMSOL Model
Without Grating With Grating
inputP IV 2RP I R
1010input input
IP P I V V
2 2
2
10 100 100R
R
PI I RP I R R
highV
lowV
-+
-+
TransformerTransformer
3D Taper (Optical Transformer)3D Taper (Optical Transformer)
Au
Single molecule detection requires electric field enhancement of 1014
1016
1014
1012
1010
108
106
104
102
1
OpticalAntenna
Grating Coupler
Optical Transformer
2D Taper
Au
The Side ViewThe Side View
Initial Thickness
Final Thickness
Taper Angle
Au
Au
The Side ViewThe Side View
Optimizing Taper AngleOptimizing Taper AnglePo
wer
Thr
ough
put (
%)
Taper Angle (Degrees)
Where Initial Thickness = 50nm and Final Thickness = 5nm
Transformer Action in 2DTransformer Action in 2D
100 nmAir
50 nm
Final Plate Spacing (nm)
Vou
t / V
in
1 10
Transformer Action in 2DTransformer Action in 2D
100 nmAir
50 nm
Final Plate Spacing (nm)
Vou
t / V
in
1 10
E-Field Enhancement in 2DE-Field Enhancement in 2D
Eou
t / E
in
Transformer Action in 3DTransformer Action in 3D
Vou
t /
Vin
E-Field Enhancement in 3DE-Field Enhancement in 3D
Eou
t /
Ein
Single molecule detection requires electric field enhancement of 1014
1016
1014
1012
1010
108
106
104
102
1
OpticalAntenna
Grating Coupler
Optical Transformer
CitationsCitations
Pictures:
http://unitedlp.com/images/power_Lines.jpgwww.jamd.com/image/g/1714820http://www.macsparky.com/wp-content/uploads/2008/01/crowd.jpg
