metamaterials for terahertz...
TRANSCRIPT
NEAR-Lab - 1090514, gpk
NEAR-Lab Northwest Electromagnetics &
Acoustics Research
Metamaterials
for Terahertz Frequencies
Gabe Kniffin
ECE 594
Dr. Andres La Rosa
NEAR-Lab - 2040123, lmz
NEAR-Lab Northwest Electromagnetics &
Acoustics Research
Outline
•
Introduction to Terahertz
•
Introduction to Metamaterials
•
Overview of Metamaterial
Switching/Modulation of THz
•
Summary
NEAR-Lab - 3040123, lmz
NEAR-Lab Northwest Electromagnetics &
Acoustics Research
Terahertz Gap
(1)
Mickan, et.al. International Journal of High Speed Electronics and Systems, 13(2):601-676,2003(2)
Compendex
search engine http://www.engineeringvillage2.org
Journal or Conference Articles with “THz”
or “Terahertz”
in Subject/Title/Abstract (English only)
photonicsTHz gap (1)electronicsmicrowave visible x-ray
100
DC103
kilo106
mega109
giga1012
tera1015
peta1018
exa1021
zetta1024
yottaFrequency
(2)
NEAR-Lab - 4040123, lmz
NEAR-Lab Northwest Electromagnetics &
Acoustics Research
Security
Potential Terahertz Applications
Medical Monitoring/NDE
Skin cancer3
Dental4
Drug detection5
(1)http://www.qinetiq.com/home/newsroom/news_releases_homepage/2004/3rd_quarter/QinetiQ_MORI_survey_results.html(2)http://www.technologyreview.com/Biztech/17840/(3) WOODWARD ETAL , THE JOURNAL OF INVESTIGATIVE DERMATOLOGY, VOL. 120, NO. 1 JANUARY 2003(4) www.physics.gatech.edu/gcuo/lectures/UFO22THzgeneration.ppt(5) Kawase, et al. Non-destructive terahertz imaging of illicit drugsusing spectral fingerprints, Optics Express, 2549, 6 October 2003 / Vol. 11, No. 20
Integrated circuits4
(1)
(2)
NEAR-Lab - 5040123, lmz
NEAR-Lab Northwest Electromagnetics &
Acoustics Research
Why Metamaterials
for Terahertz?
•
Few natural materials with THz response
•
Potential for THz devices due to tunable material parameters
NEAR-Lab - 6040123, lmz
NEAR-Lab Northwest Electromagnetics &
Acoustics Research
Outline
•
Introduction to Terahertz
•
Introduction to Metamaterials
•
Overview of Metamaterial
Switching/Modulation of THz
•
Summary
NEAR-Lab - 7040123, lmz
NEAR-Lab Northwest Electromagnetics &
Acoustics Research
Introduction to Metamaterials
•
Veselago, 1968−
Introduced theory of materials with μ
< 0 and ε
< 0−
Predicted negative refractive index
−
“Right Handed”
vs. “Left Handed”
material
2n
HkE
EkH
c
c
HkE
EkH
c
c
V. G. Veselago. The electrodynamics of substances with simultaneously negative
values of ε
and μ. Soviet Physics USPEKHI, 10(4):509–514, January-February 1968.
NEAR-Lab - 8040123, lmz
NEAR-Lab Northwest Electromagnetics &
Acoustics Research
Introduction to Metamaterials
•
Poynting
flux reversed from phase velocity−
Radiation tension
−
Reverse doppler
effect−
Reverse Cerenkov radiation
•
Negative refraction → “superlens”
V. G. Veselago. The electrodynamics of substances with simultaneously negative
values of ε
and μ. Soviet Physics USPEKHI, 10(4):509–514, January-February 1968.
NEAR-Lab - 9040123, lmz
NEAR-Lab Northwest Electromagnetics &
Acoustics Research
Design of Materials with ε
< 0
J.B. Pendry, A.J. Holden, W.J. Stewart, and I. Youngs. Extremely low frequency plasmons
in metallic mesostructures. Physical Review Letters, 76(25):4773 –
4773, 1996.
•
Pendry
et al., 1996−
Plasma frequency, ωp
, for most metals is in UV range
−
ε
< 0
for ω
< ωp
−
3-D lattice of thin metal wires lowers ωp
via self-inductance
NEAR-Lab - 10040123, lmz
NEAR-Lab Northwest Electromagnetics &
Acoustics Research
Design of Materials with μ
< 0
J.B. Pendry, A.J. Holden, D.J. Robbins, and W.J. Stewart. Magnetism from conductors and enhanced nonlinear phenomena. IEEE Transactions on Microwave Theory and Techniques,
47(11):2075 –
2084, 1999.
•
Pendry
et al., 1999−
Proposed split-ring resonator (SRR) design
−
LC resonant behavior−
Waves couple if E vector is normal to split gap or if H vector is normal to SRR plane
−
(Real)
μ
< 0
occurs at resonance
NEAR-Lab - 11040123, lmz
NEAR-Lab Northwest Electromagnetics &
Acoustics Research
Outline
•
Introduction to Terahertz
•
Introduction to Metamaterials
•
Overview of Metamaterial
Switching/Modulation of THz
•
Summary
NEAR-Lab - 12040123, lmz
NEAR-Lab Northwest Electromagnetics &
Acoustics Research
Modulation/Ultrafast
Switching via Metamaterials
Hou-Tong Chen, Willie J. Padilla, Richard D. Averitt, Arthur C. Gossard, Clark Highstrete, Mark Lee, John F. OHara, and Antoinette J. Taylor. Electromagnetic metamaterials
for terahertz applications. Terahertz Science and Technology, 1(1):42–50, March 2008.
•
Chen et al., 2008−
Used variations on Pendry’s
SRR(a) SRR(b) “Electronic Split Ring Resonator”
(eSRR)
−
Dampened resonant response via substrate conductivity manipulation:
Ultrafast
THz switching
All electronic THz modulation
NEAR-Lab - 13040123, lmz
NEAR-Lab Northwest Electromagnetics &
Acoustics Research
Ultrafast
Switching
Hou-Tong Chen, Willie J. Padilla, Richard D. Averitt, Arthur C. Gossard, Clark Highstrete, Mark Lee, John F. OHara, and Antoinette J. Taylor. Electromagnetic metamaterials
for terahertz applications. Terahertz Science and Technology, 1(1):42–50, March 2008.
•
Linearly polarized THz probe pulses couple into SRRs
•
Femptosecond
pump beam excites carriers, shorting split gap, dampening resonance
•
2 Substrates:•
SI-GaAs
-
Long carrier lifetime•
ErAs/GaAs
nanoisland
superlattices
-
Short carrier lifetime
NEAR-Lab - 14040123, lmz
NEAR-Lab Northwest Electromagnetics &
Acoustics Research
Ultrafast
Switching of THz
Hou-Tong Chen, Willie J. Padilla, Richard D. Averitt, Arthur C. Gossard, Clark Highstrete, Mark Lee, John F. OHara, and Antoinette J. Taylor. Electromagnetic metamaterials
for terahertz applications. Terahertz Science and Technology, 1(1):42–50, March 2008.
•
SI-GaAs
substrate•
Carrier lifetime >> THz pulse duration
•
Quasi-steady state response−
~0.5 THz absorption due to metamaterial
response
−
~1.6 THz absorption due to λ/2 resonance of unsplit
SRR sides−
Metamaterial
resonance ‘switched off’
by pump beam
•
ε
< 0 near both resonant frequencies
NEAR-Lab - 15040123, lmz
NEAR-Lab Northwest Electromagnetics &
Acoustics Research
Ultrafast
Switching of THz
Hou-Tong Chen, Willie J. Padilla, Richard D. Averitt, Arthur C. Gossard, Clark Highstrete, Mark Lee, John F. OHara, and Antoinette J. Taylor. Electromagnetic metamaterials
for terahertz applications. Terahertz Science and Technology, 1(1):42–50, March 2008.
•
ErAs/GaAs
nanoisland
superlattices•
Carrier lifetime ~10 ps
within order of THz pulse duration
•
Switching recovery time measured by varying delay time between photoexcitation
and THz pulse arrival
•
Resonant behavior returns after ~ 30 ps
delay
NEAR-Lab - 16040123, lmz
NEAR-Lab Northwest Electromagnetics &
Acoustics Research
THz Modulation via Metamaterials
Hou-Tong Chen, Willie J. Padilla, Richard D. Averitt, Arthur C. Gossard, Clark Highstrete, Mark Lee, John F. OHara, and Antoinette J. Taylor. Electromagnetic metamaterials
for terahertz applications. Terahertz Science and Technology, 1(1):42–50, March 2008.
•
All electronic THz modulation•
eSRRs
embedded in n-type GaAs
substrate in Schottky
diode configuration•
Conductive substrate shorts split gap, dampening resonance
•
Voltage bias creates depletion region in split gap, resulting in resonance
•
ε
< 0 near 0.75 THz and > 1.75 THz
NEAR-Lab - 17040123, lmz
NEAR-Lab Northwest Electromagnetics &
Acoustics Research
Summary
•
THz a promising technology for spectroscopy, NDE, medical, and dental imaging
•
Metamaterials
allow the tailoring of material parameters to desired specifications
•
Metamaterials
potentially useful for THz devices