SILICON PHOTONICS PLATFORM FOR 50G
OPTICAL INTERCONNECTS MICHAL RAKOWSKI
IMEC, LEUVEN, BELGIUM
Photonics Summit and Workshop 2017
06 Sep 2017 - 07 Sep 2017, San Jose, CA, USA
Photonics Summit and Workshop 2017M. Rakowski
OUTLINE
Short-Reach Optical Interconnect Roadmap
Cu-to-Optical Transition Roadmap
50G NRZ Silicon Photonics Platform
Passive Devices
Modulators
Photodetectors
Optical I/O module
Transceiver Architectures and scalability
TSV integration with Silicon photonics
CMOS-SiPh Transceiver Demonstrators
Conclusion
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Photonics Summit and Workshop 2017M. Rakowski
OPTICAL VS. COPPER INTERCONNECTS
TRANSITION
ROADMAP (IMEC)
Link distance
Optical Interconnects
replacing Copper at
increasingly Shorter Reach
Datacenter [5m-10km+]
100G-400G-1.6T+
Backplane [0.5-3m]
8-16-32+ x 50G-100G
Board [5-50cm]
200Gbps+/mm
Package [1cm-10cm]
1Tbps+/mm
Interposer/Chip [1mm-2cm]
10Tbps+/mm Copper
Optical
?1Tbps/mm
100Gbps/mm
10Tbps/mm
I/O Density
100Tbps/mm
10Gbps/mm
Package/ChipLogic Core-Core,
Logic-DRAM
[1mm-5cm]
1cm
Link
bandwidthMMF
SMF
BackplaneBoard-to-board
[0.5m-3m]
Source: LightCounting
10G
50G
25G
1 Mbps
1 Gbps
1 Tbps
1 Pbps
10G
40G
100G
400G
800G
200G
1.6T
3.2T
1G
2.5G
Intra-DatacenterRack-to-Rack
[5m-500m+] Inter-Datacenter[10km+]
Source: LightCounting
BoardLogic Package-to-Package
Logic-DRAM array
[5cm-0.5m]
Source: Intel
6.4T
100G
400G
800G
200G
1.6T
3.2T
6.4T
100G
400G
800G
200G
1.6T
3.2T
6.4T
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Photonics Summit and Workshop 2017M. Rakowski
OPTICAL I/O MODULE ROADMAP
1. Unclear if future CMOS nodes will support baud rates beyond 50Gbd
2. PAM-4 acceptable for long links, but NRZ modulation preferred for short, latency sensitive links
At 50Gb/s channel speed, Wavelength Division Multiplexing is essential for module scaling
• 8+ WDM-channels likely required, even if 2x 8-parallel fibers are used per module DWDM
NEED FOR WAVELENGTH DIVISION MULTIPLEXING
Host IC CMOS node 28-20nm 16/14nm iN10 iN7 iN5
Switch I/O Bandwidth 3.2Tb/s 6.4Tb/s 12.8Tb/s 25.6Tb/s 51.2Tb/s
Year of Introduction 2016 2018 2020 2022 2024
Optical I/OModule Bandwidth
100-200Gb/s 400Gb/s 800Gb/s 1.6Tb/s 3.2Tb/s
Channel Data Rate 25Gb/s NRZ50Gb/s PAM-4
50Gb/s NRZ100Gb/s PAM-4
50Gb/s NRZ100Gb/s PAM-4
50Gb/s NRZ100Gb/s PAM-4
50Gb/s NRZ100Gb/s PAM-4
Optical I/O Energy 10pJ/bit <5pJ/bit <2pJ/bit <1pJ/bit <500fJ/bit
WDM ChannelsDuplex fiber, PAM-4
8x fiber (PSM-4), NRZ16x fiber (PSM-8), NRZ
41
421
842
1684
32168
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Photonics Summit and Workshop 2017M. Rakowski
SILICON PHOTONIC INTEGRATION
Silicon PICs
Fabrication in CMOS fabs [200mm/300mm]
Large Si/SiO2 refractive index contrast of ~2 [scalable PIC density]
Advanced Si patterning capability [193(i), nanometer scale accuracy]
(Si)Ge epitaxy [photodetectors/modulators]
Low resistance contacts to Si [high-speed optical devices]
Volume scalability [>1M units/year] & Efficiencies of scale [cost]
Wafer-scale 3-D packaging and assembly [TSVs, micro-bumps, ...]
No monolithic integrated optical gain/lasing [need for hybrid solution]
BENEFITS AND DRAWBACKS
Silicon Photonics = Leverage existing CMOS infrastructure for Photonic Integration5
Photonics Summit and Workshop 2017M. Rakowski
IMEC’S SILICON PHOTONICS PLATFORM50G SILICON PHOTONIC INTEGRATED CIRCUIT TECHNOLOGY
56G Ge Electro-Absorption
Modulator
56Gb/s eye
diagram
56G Silicon Ring
Modulator56Gb/s eye
diagram
8+1-channel DWDM (De-) Multiplexing Filter
Surface-Normal Coupler50G Ge Photodetector50Gb/s eye
diagram
56G Silicon Mach-Zehnder Modulator
Edge Coupler
Co-integration of high performance 50G active and passive blocks in a single platform
Implemented in 200mm SOI (90/130nm) and 300mm (<28nm)
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50G NRZ SILICON PHOTONICS PLATFORMPASSIVE DEVICES
Photonics Summit and Workshop 2017M. Rakowski
WAVEGUIDESSUB-MICRON SOI WIRE WAVEGUIDES
Loss vs Bend Radius
nSi~3.45
nSiO2~1.45
450nm
220nm
SiSiO2
-1.84 ( 0.1) dB/cm
-25
-30
-40
-50
-60
spiral length [cm]0 5 10 15 20
Tra
nsm
issio
n [d
B]
-35
-45
-55
10 mm
High index-contrast Si waveguide technology enables
compact photonic circuits (~µm bends)
But, more sensitive to sidewall roughness (propagation
loss ~ 0.1-1dB/cm)
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Photonics Summit and Workshop 2017M. Rakowski
Peak Loss vs Bandwidth
FIBER COUPLING INTERFACESSURFACE NORMAL GRATING COUPLERS
Fiber Grating Couplers: <3dB insertion loss over 30nm optical bandwidth to Standard Single Mode Fiber
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Photonics Summit and Workshop 2017M. Rakowski
FIBER COUPLING INTERFACESEDGE COUPLERS
Broadband
Relatively insensitive for polarization
Smaller spot size complicate packaging
Additional process steps and stack layers
Wafer-scale testing not straightforward
Si Oxy-Nitride Edge Couplers: <2dB insertion loss over 100nm
to Specialty Fiber (3um Mode Field Diameter)
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Photonics Summit and Workshop 2017M. Rakowski
SILICON WAVELENGTH MULTIPLEXING DEVICESRING-BASED DWDM FILTERS
𝑚 ⋅ 𝜆𝑟𝑒𝑠 = 𝐿𝑅𝑇 ⋅ 𝑛𝑒𝑓𝑓
Filter resonance condition
Input Waveguide
8x Drop Waveguides
8x Cascaded Ring Filters
Spectral Response 8-Channel FilterInput Waveguide
Drop Waveguide
Ring
Waveguide
lres
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Photonics Summit and Workshop 2017M. Rakowski
8+1-channel DWDM Demultiplexing Filter
Transmission Spectrum
Polarization diversity scheme
8 channel (de)MUX filter, using cascaded
ring filters
Double-ring filter design with flat-top
response
~3dB insertion loss, ~20dB crosstalk
Collective, low-power thermal tuning
SILICON WAVELENGTH MULTIPLEXING DEVICESRING-BASED DWDM FILTERS
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50G NRZ SILICON PHOTONICS PLATFORMSILICON MODULATORS
Photonics Summit and Workshop 2017M. Rakowski
SIPH OPTICAL MODULATOR OPTIONS
Df(V)
Df(-V)
Si Mach-Zehnder Modulator
Tra
nsm
ission
PIN
P1
P0
Applied Voltage
IL
ER
Vp
Vpp
ER
IL
Modulation
efficiency (pm/V)
λr
P0
P1
Optically broadband
Thermally robust
Large device (L~1mm)
Large dynamic power
L Dl(V)
Si Ring Modulator
2R
Optically narrowband (<1nm)
Thermally sensitive (<1K)
Compact device (R~5mm)
Low dynamic power (1Vpp)
Ge Si Electro-Absorption
Modulator
L
Optical Bandwidth (<30nm)
Thermally insensitive (<30K)
Compact device (L~60mm)
Low dynamic power (2Vpp)
~IL
~ER
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Photonics Summit and Workshop 2017M. Rakowski
SILICON MACH-ZEHNDER MODULATORTRAVELING-WAVE MZM DESIGN AND PERFORMANCE
50Gb/s Eye diagram with
2.5Vpp
Input Output
Heaters
P G S G S G P
Phase
shifter
Parameter Typ. Value
Operation Wavelength 1550nm
EO Bandwidth (S21) f3dB 27GHz (at -1V)
Optical Loss 8.2 dB/cm (at 0V)
Modulation efficiency V𝜋 11 V
Optical Insertion Loss IL -2dB (excludes bias-included loss)
Dynamic Extinction Ratio ER ~2.2dB (for 2.5Vpp single-ended drive)
Phase-Shifter Length L 1.5mm50Gb/s Eye diagram with
2.5Vpp
-20
-15
-10
-5
0
0 10 20 30 40 50
No
rmal
ize
d S
21
[dB
]
Frequency [GHz]
S21 @ 0V S21 @ 1VElectro-optic S21 response
g w g
Ground Signal Ground
Trench
width
Waveguide
width
BOX
Substrate
P+ PBODY P N N+NBODY
Body
width
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Photonics Summit and Workshop 2017M. Rakowski
ER for
1V (dB)
IL (dB)
Modulation efficiency
(pm/V)
Transmission spectra
wavelength (nm)
Po
ut (d
Bm
)SILICON RING MODULATORDESIGN SPECIFICATIONS
Targeted Specifications
Ring radius 5 um
Quality Factor 2k-10k
Modulation Efficiency >50 pm/V
Modulation Bandwidth f3dB >40 GHz
Transmitter Penalty (@1Vpp) <6 dB
Heater efficiency >0.2 nm/mW
Heater Control RF Signal Ground
Light in Light out
10mm
Tungsten Heater
Microscope
Image
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Photonics Summit and Workshop 2017M. Rakowski
SILICON RING MODULATOR
1552.8 1553.0 1553.2 1553.4 1553.6 1553.8-65
-60
-55
-50
-45
-40
-35
-30
-25
Tra
ns
mis
sio
n [
dB
m]
Wavelength [nm]
-2.0V
-1.5V
-1.0V
-0.5V
0.0V
0.5V
Q-factor
Voltage
swing
(-1V to
0.5V)
Modulation
efficiency (pm/V)
ER at min TP
(dB)
IL at min TP
(dB)
Min Transmitter
Penalty (dB)
*3dB BW
(GHz)
Heating
efficiency
(nm/mW)
3200 1.5 45 2.6 6.0 11 47 0.284
1550 1555 1560 1565-35
-30
-25
-20
-15
-10
-5
0
5
Tra
ns
mis
sio
n [
dB
m]
Wavelength [nm]
0 V
0.25 V
0.5 V
0.75 V
1 V
1.25 V
1.5 V
1.75 V
0 10 20 30 40 50-18
-15
-12
-9
-6
-3
0
Re
lati
ve
ele
ctr
o-o
pti
ca
l S
21
[d
B]
Frequency [GHz]
1552.85 nm
1552.95 nm
1553.05 nm
1553.15 nm
S11-measurement
*Modulation bandwidth reported at wavelength with maximum S21 magnitude
1552.8 1553.0 1553.2 1553.4 1553.60
5
10
15
20
25
ER
/IL
/TP
[d
B]
Wavelength [nm]
Extinction ratio
Insertion loss
Tx penalty
Electro-Optic Response (DC) ER, IL and TP Electro-Optic Response (RF) Thermo-Optic Response (DC)
TYPICAL PERFORMANCE
50G Ring Modulator with Integrated Heater
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Photonics Summit and Workshop 2017M. Rakowski
SILICON RING MODULATOR ELECTRICAL MODEL
Bias Cj (fF) RS (Ohm) Cox (fF) RSi (Ohm) Cm (fF)
Fitted value 0V 24 68 49 1100 6.5
S11-measurement S11-fitting
Cm: capacitance of metal pads
COX, RSi: substrate capacitance and resistance
Cj, Rs: capacitance and resistance of RM
S11-measurement S11-fitting
Real
Imag
Ele
ctri
cal S1
1Frequency [GHz]
Input
PortRSRSi
COX
Cm
Electrical equivalent circuit model
Cj
MEASURED S11 VS. ELECTRICAL MODEL FITTING
Fitted parameters
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Photonics Summit and Workshop 2017M. Rakowski
Ring
modulator
type
Q-factorModulation
efficiency (pm)
Transmitter Penalty
for 1.5Vpp swing (dB)
Measured f3dB
(GHz)
High-Q 9900 45.2 6.9 16.2
Medium-Q 3500 61.8 10.1 35
Low-Q 2200 67.6 11 47
Trade-off betweenTransmitter Penalty and Modulation
Bandwidth.
f3db =
47GHz
SILICON RING MODULATOR BANDWIDTH VS. TRANSMITTER PENALTYDETERMINED BY RESONANCE QUALITY FACTOR
2
_3
2
_3
2
3
111
QdBRCdBdB fff
RCf RCdB p2/1_3
rQdBf p2/1_3
(cavity photon lifetime)
cQr pl 2/
Modulation Bandwidth f3dB
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Photonics Summit and Workshop 2017M. Rakowski
SILICON RING MODULATOR 50-56GB/S NRZ EYE DIAGRAMS
50/56G MUX, PRBS 2e31-1, laser power=10dBm
Measured with 50Ohm terminated probe
Oscilloscope optical module with 40GHz bandwidth
50Gb/s, 1VppVbias= 0V, ER=4.7dB, SNR=5.2
50Gb/s, 2.5VppVbias= 0V, ER=5.4dB, SNR=6.8
50-56Gb/s open eye diagrams from 1Vpp drive swing
56Gb/s, 1.5VppVbias= -0.25V, ER=4.1dB, SNR=5.2, 1544.67
56Gb/s, 1VppVbias= 0V, ER=4.5dB, SNR=4.7, 1544.67
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Photonics Summit and Workshop 2017M. Rakowski
GESI ELECTRO-ABSORPTION MODULATOR
Anode
Cathode
Light
in
Light
out
Top view
Optical absorption vs. wavelength and bias voltage
Simulated E-field at 0V Simulated E-field at -2V
Reverse bias p-i-n GeSi diode 11kV/cm at ON state 60kV/cm at OFF state
Si
Ge(Si)
n i p
N+ Si
contactP+ Si
contact
Device cross section, perpendicular to light propagation
Doping Profile
WORKING PRINCIPLE & DESIGN
Franz-Keldish effect: modulate optical absorption coefficient in
Ge(Si) by applied electric field
Ultra-fast effect (~ps), RC limited
Implemented by reverse-biased p-i-n diode in GeSi waveguide
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Photonics Summit and Workshop 2017M. Rakowski
GESI EAM STATIC MEASUREMENTSTYPICAL EXTINCTION RATIO, INSERTION LOSS, TRANSMITTER PENALTY
Static modulator response spectrum
(ER and IL) vs drive swing
Optimum operation point close to 1550nm for GeSi EAM (where ER=4.6dB, IL=4.2dB for 2Vpp)
Absirbtion vs wavelength
GeSi – device (Si = 0.74%)
LPP = 𝑷𝑶𝒖𝒕 𝟏 −𝑷𝑶𝒖𝒕(𝟎)
𝟐 𝑷𝒊𝒏
Link Power Penalty (LPP) spectrum
vs drive swing
ER = 5.3dB and IL =5.2dB
(2Vpp swing at 1555nm)
Absorption coefficient increases with applied field
Sub-picosecond effect
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Photonics Summit and Workshop 2017M. Rakowski
GESI EAM STATIC MEASUREMENTS
Operation wavelength shifts with temperature to longer wavelength (0.82nm/K)
GeSi EAM device is not temperature insensitive beyond ~30K variations
TEMPERATURE DEPENDENCE
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Photonics Summit and Workshop 2017M. Rakowski
GESI EAM DYNAMIC MEASUREMENTSSMALL SIGNAL RF PERFORMANCE
Electro-Optic S21 response
Electrical S11 response
3dB bandwidth is beyond 50GHz under reverse bias above -1V
The extracted R, C from EAMs indicate the device speed is RC limited
The GeSi EAM represents a very small capacitive load of Cj < 15fF
Electrical/Optical response strongly depends on bias voltage and optical
power
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Photonics Summit and Workshop 2017M. Rakowski
GESI EAM EYE DIAGRAM MEASUREMENTS
1.5Vpp, ER = 2.55dB 2.0Vpp, ER = 3.29dB 2.5Vpp, ER = 3.89dB
56GB/S NRZ @1550NM
Open eye diagram at 56Gb/s NRZ-OOK data rate
PRBS data stream, length 231-1
Measured with 50Ohm terminated, 50GHz RF probe
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50G NRZ SILICON PHOTONICS PLATFORMGE PHOTODIODE
Photonics Summit and Workshop 2017M. Rakowski
GE WAVEGUIDE PHOTODETECTORGE P-I-N DIODE
Responsivity: > 0.85A/W at -1V
O/E 3dB BW > 50GHz
Dark current: 10nA at -2V
Capacitance < 20fF
56Gb/s, -2V, 1565nmElectro-optical S21 response
Frequency (GHz)
“VPIN” GePD
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Photonics Summit and Workshop 2017M. Rakowski
IMEC’S SILICON PHOTONICS PROTOTYPING OFFERING
28
BUILD YOUR OWN PROTOTYPE IN IMEC’S OPEN PLATFORM TECHNOLOGY!
Accessing imec’s 200mm Si Photonics Platform (iSiPP50G)
Both MPW and Fully Dedicated Runs
Silicon Validated PDK v2.2.0 is available
Supported by various EDA tools
Interested? Get in touch! MPW http://www.europractice-ic.com/, Dedicated: [email protected]
OPTICAL I/O MODULE
ARCHITECTURE AND SCALING
OPTIONS
Photonics Summit and Workshop 2017M. Rakowski
PROPOSED OPTICAL I/O MODULE ARCHITECTURE
30
HYBRID ASSEMBLY ON SILICON PHOTONICS INTERPOSER
TSV
MOD PD (de)MUXLC FC
DFB LD Array
CMOSFiber Array Coupler
Si Photonics Interposer
DRV TIA CTRL
Cross Section Schematic
• DFB-LD = Distributed Feedback Laser Diode
• LC = Laser Coupler
• DRV = Modulator Driver
• TIA = Trans-Impedance Amplifier
• CTRL = Control Circuit
• MOD = Electro-optic Modulator
• PD = Photodetector
• TSV = Through-Silicon Via
• MUX = Wavelength Multiplexer
• FC = Fiber Coupler
Optical Module
In-Package Optical Module Integration (400Gb/s+)
Switch ASIC/FPGA
package
Photonics Summit and Workshop 2017M. Rakowski
OPTICAL TRANSCEIVER SCALING
Faster Channels
25G
50G
100G
4l8l
16l1core
8core
16core
1-bit 1l
2-bit
4-bitPAM-16 (LightWire/Luxtera)
10G
J. Sakaguchi, et al, "19-core fiber transmission of 19x100x172-Gb/s SDM-WDM-
PDM-QPSK signals at 305Tb/s," OFC2012, PDP5C.1.
Focus for very-short reach
interconnects:
Faster and More Channels
More bits per Symbol
Amplitude: PAM-X
Phase and Amplitude: DP-QPSK, QAM-X, ...
More Channels
Parallel (Single-Mode) Fiber [PSM]
Multi-Core Fiber, Spatial Division Multiplexing [SDM]
Wavelength Division Multiplexing [WDM]
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Photonics Summit and Workshop 2017M. Rakowski
OPTICAL CHANNEL SCALING
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4-CHANNEL TRANSCEIVER EXAMPLES
PSM-4
Parallel Single Mode Fiber
CWDM-4
Coarse Wavelength Division Multiplexing
Channel Modulation
100GbE 4x25Gb/s NRZ
200GbE 4x50Gb/s PAM-4
Photonics Summit and Workshop 2017M. Rakowski
SDM-8
Spatial Division Multiplexing
DWDM-8
Dense Wavelength Division Multiplexing
OPTICAL CHANNEL SCALING
33
8-CHANNEL TRANSCEIVER OBJECTIVE
Channel Modulation
400GbE8x50Gb/s NRZ or PAM-4
4x100Gb/s PAM-4
800GbE16x50Gb/s NRZ
8x100Gb/s PAM-4
TSV INTEGRATION WITH
SILICON PHOTONICS
Photonics Summit and Workshop 2017M. Rakowski
TSV INTEGRATION
10x100 TSV integration
Pitch 20-60µm
WITH SILICON PHOTONICS
Si Photonics interposer on
carrier wafer
TSVMOD PD (de)MUXLC FC
CMOS
Fiber Array CouplerSi Photonics Interposer
DRV TIA CTRL
100µm
100µm
10µm
TSV
BSRDL
100µm
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BSRDL and passivation
Photonics Summit and Workshop 2017M. Rakowski
TSVHIGH SPEED PERFORMANCE
Inse
rti
on
lo
ss (
dB
)
Very low RF losses for TSV at 50GHz
L
100µm
100µm
High-signal integrity at 50Gb/s NRZ
L=300µm
L=100µm
L=300µm
L=1000µm
Small Signal (measured) Large Signal (simulated)
36
SIPHTRANSCEIVER DEMONSTRATORS
Photonics Summit and Workshop 2017M. Rakowski
ULTRA-COMPACT 16X 56GB/S GESI EAM-PD ARRAY
16x 56Gb/s
GeSi EAM
array
16x 56Gb/s
GeSi PD array
1x16 MMI splitter tree
1 input,
16 TX output
16 RX input
100𝜇m pitch
0.7mm
3mm
61-channel Pitch-Reducing Optical Fiber
Array (PROFA, Chiral Photonics)
37um
100um
100x50um GeSi
EAM and PD
Diode: 600nm
wide, 40um long
50um37-channel grid of fiber
grating couplers, 37um
pitchInput
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Photonics Summit and Workshop 2017M. Rakowski
PROFA and Packaging by Chiral Photonics
0.7mm
3.0
mm
PACKAGINGPITCH-REDUCING OPTICAL FIBER ARRAY (PROFA)
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Photonics Summit and Workshop 2017M. Rakowski
GeSi EAM optical transmission GeSi EAM to GeSi PD Loopback
GeSi EAM driving voltage (peak to peak): 2.5V, 56Gb/s (PRBS31)
Bias GeSi PD: -2.5V
GeSi EAM array Dynamic extinction ratio (ER) in the range of 2.7-3.3dB
GeSi EAM to GeSi PD array SNR in the range of 3.05-3.92
GESI EAM TO GESI PD LOOPBACK TRANSMISSION TEST16 CHANNEL LINK UNIFORMITY ANALYSIS AT 56GB/S NRZ
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Photonics Summit and Workshop 2017M. Rakowski
GESI EAM-PD AT 100GB/S First SINGLE-WAVELENGTH 100Gb/s NRZ-OOK modulation demo in Silicon Photonics
Collaboration with100Gb/s Eye Diagrams
(III-V discrete PD)
B2B
500m
SM
F
BER below threshold for FEC
2km
DSM
F 100Gb/s Eye Diagram
for GeSi EAM-to-GeSi PD
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Photonics Summit and Workshop 2017M. Rakowski
RING MODULATOR DRIVER IN 28NM CMOSCIRCUIT CONCEPT AND WIRE-BONDED PROTOTYPE
SiPh die with ring modulator array
Wirebond
Fiber in
Polarization
controller
Tunable
Laser
(12dBm)
Fiber out
EDFA (6dB)
Sampling
Oscilloscope
40GHz BW
Optical Filter
-
67GHz - 50Ω GSG probe
PPG + MUX
56 Gb/s
Wirebond
Wire-bonded CMOS-SiPh Prototype
dataEn Cathode Stage
Anode Stage
MP2
MN3
MP3
data
Bond Pad
Bond Pad
Cathode Stage
Anode Stage VDD
VSSEn
AE
drv2
drv1
MP4MP5
Ring
Modulator
Cpad=60fF
Cpad=60fF
MP1
MN1
MN2
65µm
Anode
Cathode
V
t
VDD
-VDD
Differential voltage
swing
Invertor-based Differential Driver Concept
Target load per stage: C=150fF
Target data rate = 50Gb/s (1.1V)
Voltage swing (~1.7 VDD)
Single driver supply
Driver supply:
VDD=1.1V
Ebit = 610 fJ/bit
50Gb/s NRZ
50Gb/s NRZ, PRBS07
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Photonics Summit and Workshop 2017M. Rakowski
CONCLUSIONS
Interconnect requirements for high bandwidth density, low-power and low-cost are pushing
optical interconnects to shorter distances
Supporting many modulation schemes & wavelength bands considered for future datacenters
single-mode interconnects
Silicon Photonics for short-reach optical interconnects
50G NRZ optical modulation and detection rates are readily achieved
SiPh active devices can be directly driven by advanced CMOS: low capacitance and low drive voltages
Tight integration with host CMOS ICs using 3-D assembly
Low die cost and volume scalability (Spatial and Wavelength Division Multiplexing)
Main challenges
Low-cost laser array integration on SiPh interposer
Self-aligned fiber array assembly
Thermal stability (passive and active devices) and optical insertion loss
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Photonics Summit and Workshop 2017M. Rakowski
ACKNOWLEDGEMENT
This work is supported by
imec’s industry-affiliation R&D program on Optical I/O
EU Funding: FP7-2007/2013 (318178-PLAT4M), H2020-ICT-2015 (688172-STREAMS) and (688510-
TERABOARD)
imec’s Optical I/O and Si Photonics team:P. Verheyen, M. Pantouvaki, B. Snyder, P. De Heyn, G. Lepage, S. Balakrishnan, N. Golshani, J. De Coster, H.
Chen, A. Srinivasan, S. Lardenois, S. Agarwal, P. Absil, J. Van Campenhout and many more
Further information available in these papers:[1] M. Pantouvaki, et al. “56Gb/s Ring Modulator on a 300mm Silicon Photonics Platform”, TH2.4.4, ECOC 2015
[2] A. Srinivasan, et al. “56Gb/s Germanium Waveguide Electro-Absorption Modulator”, J. Lightw. Tech., 2015
[3] M. Pantouvaki, et al. “50Gb/s Silicon Photonics Platform for Short-Reach Optical Interconnects”, OFC 2016
[4] M. Rakowski et al, “A 50Gb/s, 610fJ/bit Hybrid CMOS-Si Photonics Ring-based NRZ-OOK Transmitter ,” OFC 2016
[5] S. Agarwal et al, “Wavelength Locking of a Si Photonic Ring Transmitter using a Dithering-based OMA Stabilizing Feedback Loop ,” OFC 2016
[6] H. Chen et al, “-1 V Bias 56 Gbps Germanium Waveguide p-i-n Photodetector with Silicon Contacts,” OFC 2016
[7] P. De Heyn et al, “Ultra-Dense 16x56Gb/s NRZ GeSi EAM-PD Arrays Coupled to Multicore Fiber for Short-Reach 896Gb/s Optical Links”, OFC 2017
[8] J. Verbist et al, “First Real-Time 100-Gb/s NRZ-OOK Transmission over 2km with a Silicon Photonics, Electro-Absorption Modulator”, OFC 2017
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