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Rapid Prototyping of Photonic Crystal based THz Components towards Integrated THz Micro-System Ziran Wu Department of Physics Department of Electrical and Computer Engineering [email protected]. Outline. 1. Background / Motivations Photonic Crystal based Components - PowerPoint PPT Presentation
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Rapid Prototyping of Photonic Crystal Rapid Prototyping of Photonic Crystal based THz Components towards based THz Components towards
Integrated THz Micro-SystemIntegrated THz Micro-System
Ziran WuZiran Wu Department ofDepartment of PhysicsPhysics
Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering
[email protected]@email.arizona.edu
OutlineOutline 1
Background / Motivations
Photonic Crystal based Components
Polymer-Jetting Rapid Prototyping
Realizations of Various THz Components
Components Systematic Integration
Conclusions
THz BackgroundTHz Background
* D. Arnone et. al., Physics World, 0953-8585, April 2000* Optics.org, analysis article, Oct. 28, 2002
2
Unallocated communication region
Gigabit data capacity
High bandwidth
Scattering loss < optical regime
Coverage in IR and optical blind conditions
Concealed object screening
THz bio-medical image: Identify tissue, tumor, DNA, etc.
THz chemical signatures: Explosives
* B. Ferguson, XC. Zhang, Nature Mater., 1, 26 (2002)* Peter H. Siegel, IEEE Trans. Microwave Theory Tech., 50, 910 (2002)
MotivationsMotivations 3
We need THz componentsSource, detector, filter, waveguides, antenna, quasi-optics, materials…
We need integration of componentsPre-alignments, packaging, systematic fabrication…
We need universality and customizabilityPlug-and-play, easy customization…
We need THz rapid prototyping
THz Micro-system
DUI
ResultsSource Detector
Photonic Crystal based ComponentsPhotonic Crystal based Components 4
Photonic Crystal (PhC)
Periodic arrangement of dielectric/ metallic structures
Bragg Diffraction among lattices
Forbidden wave propagation in certain frequency band
Scalable dimensions with frequency
Band Gap
THz thermal radiation source
* H. Xin et al, IEEE Trans. Antennas Propag., 56, 2970 (2008)
Normal Planckspectrum from amorphous object
IR
Inte
ns
ity Enhanced THz
emission
3-D Photonic CrystalRadiation Core
PBG structure optimized to generate strong emission peak in the THzband.
Inte
ns
ity
Normal Planckspectrum from amorphous object
IR
Inte
ns
ity Enhanced THz
emission
3-D Photonic CrystalRadiation Core
PBG structure optimized to generate strong emission peak in the THzband.
PBG structure optimized to generate strong emission peak in the THzband.
Inte
ns
ity
PBG fiber electron accelerator
* C. Sears et al, Proceedings PAC07, THPMS052, Albuquerque, NW, 2007
PBG Components ContinuedPBG Components Continued 5
Antenna with PhC substrate
* Peter de Maagt, et. al., IEEE Trans. Antennas Propag., 51, 2667 (2003)
* K. F. Brakora et. al., IEEE. Trans. Antenn. Propag., 55, 790 (2007)
Woodpile defect horn antenna
* A. Weily et. al., IEEE Trans. Antenn. Propag. 87, 151114 (2005)
Sub-wavelength effective-medium lens
Line-defect waveguide and bend
* K. Busch, Phys. Report 444, 101 (2007)* Nielsen et.al.,OTST-2009, MB5, March 2009
THz 3-D Rapid PrototypingTHz 3-D Rapid Prototyping 6
Objet (TM) polymer jetting prototyping
Layer-by-layer printing of structures
Printing resolution 42um (x) by 42um (y) by 16um (z)
UV curable model material Support material removable by water flushing (Matt mode)
Non-support-material printing available (Glossy mode)
Possibility of mixing various printing materials to achieve arbitrary spatial material properties
Rapid prototyping of arbitrary shapes
Alignment and assembly not necessary
Mass production achievable with very low cost
Build Materials CharacterizationBuild Materials Characterization 7
THz Time Domain Spectrometer
THz DetectorTHz Transmitter
Collimating Optics
Dispersion Compensation Ultra-fastLaser
Control Unit
* Ziran Wu, J. App. Phys., 50, 094324 (2008)
Photoconductive antennas as transmitter/receiver
Ultra-fast gating enables time-domain measurement
Covering 50GHz to 1.2THz with 10GHz resolution
Transmission / Reflection setup available
Build Materials THz PropertiesBuild Materials THz Properties 8
Multiple-reflection excluded by using thick slabs
Comparable EM properties in one family of polymers
Large enough refractive index contrast to open PBG Acceptable material loss
100 150 200 250 300 350 400 450 500 5502.6
2.65
2.7
2.75
2.8
2.85
Frequency (GHz)
Rea
l Per
mit
tivi
ty
VeroBlackVeroGreyVeroWhite
100 150 200 250 300 350 400 450 500 5500
0.01
0.02
0.03
0.04
0.05
0.06
0.07
Frequency (GHz)
Lo
ss T
ang
ent
VeroBlackVeroGreyVeroWhite
Vero Family
Printed woodpile prototype
Dielectric / metallic rods with woodpile stacking formations Square rod width w= 352um and periodicity d= 1292um Printing took about 30 minutes; Consumable cost of approximately $10
Excellent agreements with simulations on both gap positions and depths
Filter: Woodpile StructureFilter: Woodpile Structure 9
* S.Y. Lin et.al,, Nature 394, 251 (1998)
Printed Johnson Structure prototype
Filter: Johnson StructureFilter: Johnson Structure 10
* S. G. Johnson and J. D. Joannopoulos, Appl. Phys. Lett. 77, pp. 3490-3492, 2000
Hole layer – air holes in dielectric Rod layer – dielectric rods in air Triangle lattice formation in each layer
Practically difficult to fabricate
Triangular lattice constant x= 1346um Air hole radius r= 500um Air hole height h= 1713um Rod / hole layer height t= 1071um
Fabrication well verified by characterization* Ziran Wu, Opt. Express, 21, 16442-16451 (2008)
Triangular-lattice array of air cylinders in a dielectric background Center core defect to form the wave tunnel Defect modes within the band gap of the complete PhC* 90% energy concentration in the core low radiation and material losses
Waveguide: Hollow-core PCF DesignWaveguide: Hollow-core PCF Design 11
Energy Distribution
* MIT Ab-Initio MPB package
Cross-Section View
HE11 mode
Band Gap 1
Band Gap 2
Only modes above the light line can propagate
Wave vector kza/2Pi
F
req
uen
cy f
a/c
0
PEC circular waveguide, TE11 mode feeds 84mm long polymer PBG waveguide Lattice pitch 3mm, air hole radius 1.3mm, center core radius 4.2mm Transmission loss as low as 0.04 dB/mm in 1st pass-band; Low return loss
Waveguide: Wave-port SimulationWaveguide: Wave-port Simulation 12
80 100 120 140 160 180 200 220-40
-35
-30
-25
-20
-15
-10
-5
0
Frequency (GHz)
S-p
aram
eter
(d
B)
S21
S11
Band Gap 1
Band Gap 2 2
21
2
11
| |ln( ) /( )
1 | |
Sl
S
Power Loss Factor
Identical coupling to free space at input and output interfaces Transmitted power exponentially decays as waveguide length increases (Neglect multiple-reflections) Calculated loss matches well with wave-port simulation
Waveguide: Gaussian Beam ExcitationWaveguide: Gaussian Beam Excitation 13
100 105 110 115 120 125 1301.26
1.28
1.3
1.32
1.34
1.36
1.38
1.4
1.42
Waveguide Length (mm)
Lo
g (
Tra
nsm
itte
d P
ow
er)
60 80 100 120 140 160 180 200 220 2400
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Frequency (GHz)
Po
wer
r lo
ss f
acto
r (d
B/m
m)
Waveport
Beam IncidenceGaussian BeamIncidence
Transmitted PowerEvaluation Plane
Beam waist 3mm ( 90% coupling to HE11 mode)
Semi-log plotSlope = Power Loss Factor
* GEMS conformal FDTD package
112GHz
Modal field overlapping with Gaussian beam get coupling efficiency Optimum beam waist ~ 2.7mm, over 90% coupling to HE11 mode Plano-convex lens fabricated by rapid prototyping to reach optimal beam size
Waveguide: Modal Simulation / CouplingWaveguide: Modal Simulation / Coupling 14
Mode simulation based on effective index method
Modal E-field Profile
74% power coupled to HE11 modewith a beam waist of 4.2mm
* Lumerical MODE Solution
Waveguide: Fabrication and Bench SetupWaveguide: Fabrication and Bench Setup 15
Fabricated THz waveguide samples (Glossy modes)
Quasi-optics to focus the beam waist to 2.7mm
Waveguides of 50, 75, 100, 125, and 150 mm long characterized Time-gating ensures no multiple reflection in the calculation Guided mode resonance seen in all waveforms Four pass bands clearly show up around 105, 123, 153, and 174 GHz
Waveguide: Characterization ResultsWaveguide: Characterization Results 16
100 200 300 400 500 600 700 800 900 1000-1.2
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
Time delay (ps)
Fie
ld m
agn
itu
de
(V)
Reference50mm75mm100mm125mm150mm
80 100 120 140 160 180 200 220 240-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
Frequency (GHz)
Po
wer
Tra
nsm
itta
nce
(d
B)
50mm75mm100mm125mm150mm
Linear fitting of power (dB) vs. waveguide length to get loss factor Extracted loss agrees pretty well with the beam incidence simulation Downshift of about 7 GHz probably due to fabrication error (need support material)
Waveguide: Power Loss FactorWaveguide: Power Loss Factor 17
80 100 120 140 160 180 200 220 2400
0.05
0.1
0.15
0.2
0.25
Frequency (GHz)
Po
we
r lo
ss
(d
B/m
m)
MeasureBeam Inc
50 75 100 125 15045
46
47
48
49
50
51
52
Waveguide length (mm)
Tra
nsm
itte
d p
ow
er
(dB
)
Linear fitting at 107GHz
Antenna: Photonic Crystal HornAntenna: Photonic Crystal Horn 18
90 100 110 120 130 140 150 160 170-35
-34
-33
-32
-31
-30
-29
Frequency (GHz)
S11
(d
B)
100 110 120 130 140 150 160 1700.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Frequency (GHz)
Rad
iati
on
Eff
icie
ncy
Copper Horn
PCF Horn
Circular waveguide TE11 feedingPolymer loss: constant conductivity 0.23
4.2mm flared to 8mm aperture radii (12.4 degree)35mm optimized horn length along axis
Not bad considering1.5dB material loss
Directional beam obtained at two working frequencies Comparable main beam angle with copper horn; Side-lobe level not as low Works much better than copper horn (over-moded) at high frequency
Antenna: Radiation PatternsAntenna: Radiation Patterns 19
0 50 100 150 200 250 300 350-50
-40
-30
-20
-10
0
10
20
30
Theta Angle (Degree)
Dir
ecti
vity
(d
B)
Copper Horn
PCF Horn
114GHz
0 50 100 150 200 250 300 350-50
-40
-30
-20
-10
0
10
20
30
Theta Angle (Degree)
Dir
ecti
vity
(d
B)
Copper Horn
PCF Horn
164GHz
Far-Field Radiation Pattern of Phi= 0º Cut (x-z plane)
Transition: Waveguide-to-Planar CircuitTransition: Waveguide-to-Planar Circuit 20
Tapered cone helps impedance matching Power directed into the dielectric rod waveguide (TIR guiding)
Circular-to-square cross section transition Smooth surface generated by HFSS
Tapered wedge transit to microstrip substrate PEC flares on top and bottom shrink the field spread Mstrip single-mode operation up to 120GHz (400um trace width 127um substrate thick)
Transition: Waveguide-to-Planar CircuitTransition: Waveguide-to-Planar Circuit 21
70 80 90 100 110 120 130 140 150 160 170 180-50
-45
-40
-35
-30
-25
-20
-15
-10
Frequency (GHz)
S11
(d
B)
-6.75dB insertion loss best at 108GHz; low return loss Excluding 2.1dB waveguide loss 2.3dB loss at each transition section About 4dB more loss if polymer material loss included
70 80 90 100 110 120 130 140 150 160 170 180
-60
-50
-40
-30
-20
-10
0
Frequency (GHz)
S21
(d
B)
Mstrip connected
Mstrip disconnected
Sub-wavelength Effective MediumSub-wavelength Effective Medium 22
2 2
2 2 2 3
(1 ( 1) )(1 ( 1)( ))
1 ( 1)( 2 )
y z y y zzr r
xxeff
y x y y z x y zx zzr
a a a a aa
L L L La a a a a a a aa aa
L L L L L L
Capacitive Estimation of the Permittivity Tensor
Effective medium with artificially designed anisotropy
* K. F. Brakora et. al., IEEE. Trans. Antenn. Propag., 55, 790 (2007)
Source: Photonic Cavity ArraySource: Photonic Cavity Array 23
Array of cubes with ~ 200um sides Printed by polymer-jetting and metalized via sputtering Electroplating or electro-less deposition for 3-D metallization Complete band gaps between THz resonance frequencies Strong and sharp thermal emission at THz 500um
Source: PBG e-Accelerator at THz?Source: PBG e-Accelerator at THz? 24
Very cheap prototyping Arbitrary fiber / coupler design
Need a THz power source to drive it
* R. England et al., Bob Siemann Symposium and ICFA Workshop, July 8th, 2009
Integrated THz Micro-SystemIntegrated THz Micro-System 25
THz Micro-System
Source
FilterWaveguide
Metamaterial
THz ChipTHz
Sample
Transition to planar-circuits
Antenna
ConclusionsConclusions 26
THz rapid prototyping technique demonstrated
THz filter, waveguide, and antenna fabricated by prototyping
Characterizations of these components show good agreements with the designs
Prototype-able transition-to-planar circuit, effective medium, and source proposed and under study
Systematic integration of the aforementioned building blocks leads to THz micro-system
Acknowledgement Acknowledgement
Graduate StudentIan Zimmerman 1
For metal sputtering on cavity array
Wei Ren Ng 2
For sample fabrication and post-process
FacultyProf. Hao Xin 1
Prof. Richard Ziolkowski 3
Prof. Michael Gehm 2
For help on both EM modeling and sample fabrications
1 Millimeter Wave Circuits and Antennas Lab2 Non-Traditional Sensors Lab3 Computational Electromagnetics Lab
Thanks for your attention!
Other PhD WorkOther PhD Work
Thermal radiation from THz photonic crystals
THz characterization of carbon nanotube ensemble and on-substrate thin films
De-metallization of single-walled carbon nanotube thin film with microwave irradiation
Frequency-tunable THz photonic crystals using liquid crystal
“Lab-on-chip” transmission-line characterization circuits