Upload
others
View
5
Download
0
Embed Size (px)
Citation preview
© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
Silicon Photonics and the Datacenter
Marco Fiorentino
HP Labs05/19/2015
© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
“In the last 7 years online data increased 56 times”
Google (2009)
© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.3
Data-centric computing
Data grows faster than computation
Data-centric workloads
From performance to efficiency
Scalability
© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.4
HP’s “The Machine”
Electrons
Photons
Ions
Compute
Communicate
Store
http://www.hpl.hp.com/research/systems-research/themachine/
© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.5
almostSilicon Photonics is here
© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.6
Optical interconnects
$$$¢
100 103 104 105 10610-110-210-3
Distance (m)
Cost pressure
State of the art
Advantages
More bits per “wire” Less power per bit Better signal integrity
102
New architectures
© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.7
HP CoronaArchitecture example 1
Opticalhub
Arbitration
2 fixed drop filters
64 variable drop filters/detectors
L1-I
Core 0
Core 1
Core 2
Core 3
L1-D
L1-D
L1-I
L1-I
L1-D
L1-D
L1-I
L1 ↔
L2
Inte
rface
Hub
MC
NI
Through Silicon Via Array
Directory
L1 ↔
L2
Inte
rface
My
X-b
ar
Con
nect
ion
Pee
r X-b
ar
Con
nect
ionL2
Cache
Data&
Control
ModulatorsModulators
ModulatorsModulators
Modulators
Modulators
ModulatorsModulators
Modulators
Detectors
0123
N-1
NN+1
616263
4-waveguidebundles
Broadcast
Modulators Detectors
Splitters
Off-Chip
Modulators Detectors
Splitters
Fiber I/O’s to OCMs or Network
Package
Memory Controller/Directory/L2 Die
Processor/L1 Die
Analog Electronics Die
Optical DiepgcTSVs
Face to Face Bonds
Heat Sink
Laser
pgcTSVs
sTSVs
− Multiple-sender single-receiver links− 1 byte/flop on chip and to memory− 250W power envelope (compute + network)− 20x improvement over electrical
Vantrease, Dana, et al. "Corona: System implications of emerging nanophotonic technology." ACM SIGARCH Computer Architecture News. Vol. 36. No. 3. IEEE Computer Society, 2008.
© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.8
HP HyperXArchitecture example 2
•Crossbar used in high-radix switches•Switch enables high connectivity topology
Optical Data Crossbar128 channels
inpu
t buf
fer
& ro
utin
g
inpu
t buf
fer
& ro
utin
g
inpu
t buf
fer
& ro
utin
g
inpu
t buf
fer
& ro
utin
g
outp
utbu
ffer
outp
utbu
ffer
outp
utbu
ffer
outp
utbu
ffer
….. 128 ….
….. 128 ….Ahn, Jung Ho, et al. "HyperX: topology, routing, and packaging of efficient large-scale networks." Proceedings of the Conference on High Performance Computing Networking, Storage and Analysis. ACM, 2009.
© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.9
Technology requirements
•DWDM: bandwidth density•Silicon photonics: cost and scalability•Ring resonators: technology of choice
•Packaging evolution
SiGe Doped
Modulator OFF Modulator ON Switch Detector
III-V
Laser
Logic Connector Transceiver Logic TransceiverLogic
Transceiver
Active optical cables On-board In package
© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.10
1318.6 1318.7 1318.8 1318.9 1319-20
-15
-10
-5
0
Wavelength (nm)
Opt
ical
inte
nsity
(dB)
0V0.86V
Carrier-injection-based microring modulator
• Slow carrier dynamics pre-emphasis equalization
• Sensitive wavelength shifts closed-loop stabilization
ON
OFF
Q > 10,000
18dB
• P-I-N junction low optical loss beneficial for link power budget
• Large change in refractive index high modulation depth beneficial for link power budget
• Adjustable bias current alternative tuning mechanism
(blue-shift)
p+ Si n+ Si
Si substrate
BOX
Metal 1
Metal 2
W-plug
Optical mode
Waveguide
© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.11
Si Photonics DWDM link
Comb laser• InAs/GaAs quantum-dot Fabry-Perot laser module @ 1.3μm• Multi-channels with 80GHz spacing at operating point• Improved performance at higher temperature• high wall plug efficiency (20%)
Hybrid integration• 1st generation: wirebonding• 2nd generation: flip-chip bonding
Transmitter• Carrier-injection-based microring modulator• Driver with pre-emphasis + thermal & bias tuning
Receiver• Drop filter + Ge waveguide Photodiode (PD)• Self-adaptive data receiver + forward clock
recovery
Multi-λlight source Optical
fiber
CMOSDriver
Tuningcircuitry
Waveguide
Microring
Tx module
Optical coupler
CMOSReceiver
PD
Rx module
© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.12
Prototype 5-channel transceiver
Tx: 5 microring modulators + integrated monitor PD + heaterRx: 5 microring drop filters + integrated Rx PD + heater
Photonic chip manufactured by LETI
Footprint limited by flip-chip bonding pads and CMOS circuit (TSMC 65 nm)
1mm
2mm
2.8mm
1.7mm
Electrical I/O & power
OpticalPower supply
© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.13
Photonic IC
Metal 1
Metal 2Waveguide
Heater
Isolation trench
Tx
Rx
Flip-chip bonding pads to CMOS
Wirebonding pads to PCB
Power grid for CMOS
For high-speed modulation
For heater tuning
On-chip link
© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.14
Transmitter results
Dual-edge pre-emphasis with pulse width controlled by tunable delay cells (30ps~60ps)Cascode output stage used to meet high modulation swing requirement
© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.15
Open problems and future directions
HP sees Photonics as the future of datacom•Integration• How do we put it all together?
•Co-design• Drivers and receivers
•Fabrication• 1000s of devices on a chip?
•Power consumption and thermal
…and most importantly
Business case
Solution roadmap
Supplier ecosystem
© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.16
Acknowledgements
HP Labs• Ray Beausoleil (Group leader)• Janet Chen (SiP design and testing)
• Cheng Li (CMOS design, area estimates)• Al Davis & the architecture Group
CEA-Leti• Sylvie Menezo & the SiP team
Our collaborators• Sam Palermo at Texas A&M
• Patrick Chiang at Oregon State