Optical Antennas for Raman Spectroscopy Laura Matloff Mentor: Matteo Staffaroni (EECS) Faculty...

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

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

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


1016

1014

1012

1010

108

106

104

102

1

OpticalAntenna


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


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

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


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

http://www.jamd.com/image/g/1714820

Optical Antennas for Raman Spectroscopy Laura Matloff Mentor: Matteo Staffaroni (EECS) Faculty...

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