Woodpile Structure Fabrication for Laser Acceleration at E163
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Woodpile Structure Fabrication for Laser Acceleration at E163 Chris McGuinness Stanford – SLAC AARD ARD Seminar 02/03/09
description
Woodpile Structure Fabrication for Laser Acceleration at E163. Chris McGuinness Stanford – SLAC AARD ARD Seminar 02/03/09. Outline. Gradient Woodpile Structure Fabrication 4 Layer Structure Analysis FTIR Spectroscopy Measurements Simulations Conclusion Where things are at for E163 - PowerPoint PPT Presentation
Transcript of Woodpile Structure Fabrication for Laser Acceleration at E163
Woodpile Structure Fabricationfor Laser Acceleration at E163
Chris McGuinnessStanford – SLAC
AARD
ARD Seminar 02/03/09
Outline
• Gradient
• Woodpile Structure Fabrication
• 4 Layer Structure Analysis– FTIR Spectroscopy Measurements– Simulations
• Conclusion– Where things are at for E163– Future Experiments
Gradient
1.0 10.0 100.0Frequency (GHz)
0.01
0.10
1.00
TrappingBreakdownPulsed Heating
Gra
die
nt
(GeV
/m)
SLC
NLC
HRC MIT
CLIC
2 MV
3 MV
40 K
120 K ?
Damage Fluence
M. Mero, et. al. Phys. Rev. B 71 115109 (2005)
λ=800nm
Ben Cowan, Stanford Graduate Thesis (2007)
o Silicon
D.M. Simanovskii, et. al. PRL 91 107601 (2003)
Woodpile Band Diagram
Dielectric Accelerator Structures
Thorlabs HC-1550-2
PBG Fibers 3D Photonic Crystal (Woodpile) Gratings
Accelerating ModeTop View
Front View Side View
Ratio=1.41
1.0 10.0 100.0Frequency (GHz)
0.01
0.10
1.00
TrappingBreakdownPulsed Heating
Gra
die
nt
(GeV
/m)
SLC
NLC
HRC MIT
CLIC
2 MV
3 MV
40 K
120 K
Gradient
0
101
SiO2 Eacc=2.76 GV/m @800nm(3.75e5GHZ)
Si Eacc=337 MV/m @1550nm(1.94e5GHZ)
Al3O2 Eacc=2.0 GV/m @800nm(3.75e5GHZ)
ZnS Eacc=1.04 GV/m @5μm(6e4GHZ)
Outline
• Gradient
• Woodpile Structure Fabrication
• 4 Layer Structure Analysis– FTIR Spectroscopy Measurements– Simulations
• Conclusion– Where things are at for E163– Future Experiments
Woodpile StructureParameter Scaling*• w=.2757a• h=.3486a • λ=2.703a• Δ=.05a
w=500nm• λ=4.9μm • a=1.814 • h=632nm• Δ=91nm
w=300nm• λ=2.94μm• a=1.09μm• h=379nm• Δ=54nma
w
Δ
h
*Cowan, B. “Photonic Crystal Laser-Driven Accelerator Structures” (PhD dissertation Stanford University 2007) 77.
4
3
wa
SiO2 resist
Silicon Substrate
Silicon Substrate
SiO2poly-si
Si Substrate
Photo resist
1
2
hSiO2
5
Poly-si
Fabrication ProcessStep 1: SiO2 Deposition
• Uniformity = 1-2%
Step 2: Resist Coat
Step 3: Optical Lithography• Minimum feature size 450nm• Alignment 3σ=60nm
Step 4: Dry etch SiO2
Step 5: Poly-si Deposition
Fabrication Process6
8
7
SiO2 poly-si
Time
Fric
tion
al F
orc
e
10sec=15nm
Step 6: Chemical Mechanical Polish
Step 7: Repeat process for remaining layers
Final Step: Oxide Etch
Completed Four Layer Test Structure
October 2008
Outline
• Gradient
• Woodpile Structure Fabrication
• 4 Layer Structure Analysis– FTIR Spectroscopy Measurements– Simulations
• Conclusion– Where things are at for E163– Future Experiments
FTIR Spectroscopy Measurements
Simulation Using MPB
Finite Thickness Simulation
Reflection/Transmission(averaged over S&P polarizations, and polar angle θ, φ=0)
Simulation
Reflection/Transmission(averaged over S&P polarizations, and polar angle θ, φ=0)
Simulation vs. Measurement
Bandgap from MPB
SEM Profile Images
Simulation vs. Measurement
Bandgap from MPB
Summary
• Completed the fabrication of a four layer test structure– Verified a process which will be
used for the fabrication of a 15 layer structure with a defect
• Taken Spectroscopy measurements
• Developed simulation tools that agree well measurements
Current State and Future of E163
• Phase 1: Characterize laser/electron energy exchange in vacuum
• Phase 2: Demonstrate optical bunching and acceleration
• Phase 3: Test multicell lithographically produced structures
60 62 64 66 68 7025
30
35
40
45
Delay (ps)
Ene
rgy
Spr
ead
(LW
HM
; px
)
Run 0039
IFEL Modulation: 34.95 keVCorrelation Sigma: 0.68 ps
Laser On
Laser Off
Fit
0 2 4 6
-1
-0.5
0
0.5
1
1.5
Phase at 800nm (radians)
Centr
oid
Shift
(keV
)
0 2 4 6
85
90
95
Phase at 800nm (radians)
Energ
y S
pre
ad (
fwhm
; keV
)
0 2 4 6
-0.1
-0.05
0
0.05
0.1
Phase at 800nm (radians)
Asym
metr
y
Future ExperimentsFabrication
– 15 layer structure with defect– Couplers– Focusing Elements
Experiments– Wakefield
• Measure modes excited by bunched electron beam
– Excite defect• Measure mode profile• Measure coupling efficiency
– Net Acceleration
Acknowledgments
• E163 Collaboration– Bob Siemann, Eric Colby, Chris Sears, Ben Cowan,
Joel England, Bob Noble, Jim Spencer
• Byer Group– Bob Byer, Tomas Plettner, Alex Serpry, Patrck Liu
• NLCTA Operators– Janice Nelson, Doug McCormick
• Stanford Nanofab– Mary Tang, Mahnaz Mansourpour, Maurice Stevens,
Ed Myers, Uli Thumser, Nancy Latta
THIS IS THE END
