Advances in Optical Interconnects
Ray T. Chen
Microelectronics Research Center
The University of Texas, Aust
SanYa, China
12/22/2009
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Introduction:
Projection of Bandwidth
2
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Polymer-based Photonic Technology &
Business Structure
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Fully Embedded Board Level
Optical Interconnection
 Unique Architecture for Optical PWB (Printed Writing Board)
; All the optical components are interposed inside the PCB
Solve the package problem / Reduce Cost Effects
Micro-via
Cu Trace
45 micro-mirror
1x12 PIN
Photodiode
1x12 VCSEL
VCSEL array
12-channel Polymer
Waveguide [109 cm ]
Optical PCB
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Lamination of Optical Waveguide Film
& Integration of Thin Film VCSEL
 12-Channel Polymer Waveguide
& 45o Micro-Mirror
 Cross Section View
of Laminated Optical Layer
Optical Layer (~170 mm)
250mm
PSA (Pressure Sensitive Adhesive) Film
(100 / 200 mm)
PCB Substrate
 Cu Transmission Lines for VCSEL (or PD) Integration
VCSEL
PCB Sub
Optical Layer
PSA film
Optical layer
Top Emitting VCSEL
PCB Sub
2 mm
Cu Trans. Lines
(thickness = ~ 10 mm)
VCSEL
Optical Layer
via
- PSA (Pressure Sensitive Adhesive) Film : 100 / 200 mm
- Optical Waveguide Film Layer = ~ 170 mm
Bottom Emitting VCSEL
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Polyimide Based 1-to-48 Fanout H-tree
Optical Waveguide on Si-Substrate
(c)
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System Integration with
VCSELs and Photodiodes
Thin film waveguide on flexible substrate
VCSEL
Photodiode
L = 3200 um W = 485 um
H = 200 um
Pitch = 250 um
Aperture = 15 um, 10Gbps
L = 3335 um W = 690 um
H = 200 um Pitch = 250 um
Aperture = 70 um, 2.5Gbps
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Photonic Crystal structure in nature
Opal, the best known periodical
structure in nature.
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Gigahertz p-i-n Diode Embedded Silicon Photonic Crystal
Mach Zehnder Interferometer (MZI) Modulator
Optical Performance
electrodes
slow vg
Simulation
PCW line
defect
PCW
Key features
• Slow light in Photonic Crystal
Waveguide (PCW) to enhance
modulation by up to 40X
•Unique electrode routing for onchip integration with driver
•Faster speed due to the
enhancement of injection
current density by downscaling
the device size
Electrical Characterization
I-V curve of photonic
crystal p-i-n diode
Modulation
Depth 92%
80 μm
PCW
P
N
* Dark region: electrode/pad
Electrodes
Anode
Current injection
Modulation trace
(1GHz, square wave)
Cathode
-
+
Electrode
P+
Intrinsic region
N+
--
Lanlan9Gu, W. Jiang, X. Chen, L. Wang, and R. T. Chen “High speed
silicon photonic crystal waveguide modulator for low voltage application,”
Ray
T. Chen,
Applied Physics
Letters,
90, 071105used
(2007). with permission onl
SEM Micrographs & Key Facilities
2-D Image
3-D Image
High smoothness,
exact round shape
JEOL JBX-6000FS/E E-Beam Nano-Lithography
Rough
sidewall
without
postFocus Ion Beam (FIB)
etching
nano-polished endface
oxidation
Plama-Therm 790 Si
FEI Strata DB235
and SiO2 Reactive
Dual Beam SEM/FIB
Nano-characterization System Ion Etching (RIE)
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Progress of Silicon Nanophotonics
Integrated
APD+TIA
Campbell
1Gb/s PCW
Raman
1 Gb/sec
10Gb/sec
Modulator
λ Conv. Si Modulator Si Modulator
(20 pJ/bit)
UCLA
Intel
Intel/Luxtera
UT
39 GHz
Si-Ge Photodelector
30 GHz
Si-Ge Photo- U. Stuttgart
Dual Grating detector
Directional
Low power
IBM
Inverted
Coupling
PCW
Taper
Surrey
Modulator
NTT, Cornell
IBM & UT
PCW Loss PCW Loss PCW Loss
< 25 dB/cm < 7 dB/cm < 3dB/cm
IBM
IBM, Festa,
NTT
NTT
10Gb/s PIN
Modulator
(5 pJ/bit)
IBM
>1Gb/s CAP
Broadband 30Gb/sec
Modulator
Amplifier Si Modulator
(0.54 pJ/bit)
Cornell
Intel
UT
Si Nano- Cascaded
Hybrid
membrane Si Raman
Si Laser
Array
Laser
UCSB/intel
UIUC
Intel
20dB loss
reduction for
slot-PCW
UT
The highlight research projects are accomplished by
Nanophotonics and Optical Interconnects Research Lab at UT-Austin
2002
2003
2004
11
T. Chen, used
with permission
2005 Ray 2006
2007
2008onl
MURI-Center for Silicon Nano-Membranes
Scientific novelty and Uniqueness:
Nanomembrane lithography to form
3D well-aligned silicon
nanomembranes
Manufacturable process to form
nanowires, photonic crystal
waveguides and plasmonic
structures on nanomembranes
2D Ultracompact phase locked laser
array on silicon as a light source for
Optical Phased Array (OPA)
Ultracompact structure provides
large steering angles to ± 70o in both
azimuth and elevation directions for
Optical Phased Array (OPA)
Slow photon in PCW provides a
group index above 300 and provides
tunable delay time from 0 to 32
nsecs suitable for phased array
antenna applications
Name of Principal
Investigator
School
Ray Chen (Lead)
UT Austin
Seth Bank
UT Austin
Wei Jiang
Rutgers
Fabiab Pease
Stanford
John Rogers
UIUC
Gennady Shvets
UT Austin
Emanuel Tutuc
UT Austin
Ray T. Chen, used with permission onl
Detailed Approaches
source
wafer
Transfer
printing
of
nanomembranes that contain
nanostructured waveguides
 Demonstrated 3-layer devices
stamp
print
device
substrate
 Use electrostatic forces to align 3D
membrane stack to a small fraction of
a micron. Many variations are
possible:
• An interfacial fluid layer to allow
lateral motion
• A Langmuir-Blodgett trough is
already installed for the deposition of
mono-& oligo-layers.
 thin (<100nm) sliver of crystalline
diamond made by FIB. Then the FIB
then ‘tacked ‘ it into place again using
deposition of Pt to provide the tacks
3D-HGI
S GD
100
1st
2nd
50
rd
3
10
2
10
0
10
0
-6 -3 0 3 6
VGS(V)
IDS(mA)
IDS(mA)
200 mm
0.8
3V
0.4
2V
-2
0.0
0
1
2
VDS(V)
0V
3
Ray T. Chen, used with permission onl