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IBM Research
IBM Internal November 16, 2011 © 2009 IBM Corporation
Optical PCB Overview
Frank LibschIBM T.J. Watson Research CenterYorktown Heights, NY
2 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Outline
?System view of why optics is needed
?Potential OPCB Technologies for Next Generation HPCs
– OSA Designs
– OSA Assemblies
– Packaging
– Optical Component Characterization
3 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Optimized solutions will require detailed analysis of trade-offs
Power
CostDensity
Margin, Packaging Integration, Data-rate…
Packaging Integration, Channel Integration, Margin, Cooling, Data-rate…
Base Manufacturing Cost, Yield, Channel Integration, Data-rate, Reliability…
4 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Image courtesy of the National Center for Computational Sciences, Oak Ridge National Laboratory
Why High Performance Computing?
• Materials Science• Geophysical Data Processing• Environment and Climate Modeling• Life Sciences / Drug Discovery• Fluid Dynamics / Energy• Industrial Modeling• Financial Modeling• Transportation
Larger scale, more complex, higher resolution, multiscale PhysicsShorter time to solution ? real time response
More than 50% of Top500 systems are for industry*Growing number of flops are industry (~15% in 1990s to ~30% today)*
*www.top500.orgCourtesy L. Treinish, IBM
5 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Chip ~50% ? 30% CAGR*
Maintaining the HPC Performance Trend
1.E-01
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.E+06
1.E+07
1.E+08
1.E+09
1.E+10
1.E+11N
ov-9
2
Nov
-94
Nov
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Nov
-98
Nov
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Nov
-02
Nov
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Nov
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Nov
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Nov
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Nov
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Nov
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Nov
-16
Nov
-18
Nov
-20
Time
Per
form
ance
(Gig
aflo
ps)
Semiconductors & Pkg:~15-20% CAGR, slowing
Systems:85-90% CAGR,continuing**
Accelerators
Increasing Parallelism: ? System BW at all levels of assembly must scale exponentially
– ~(0.1-1 Byte/Flop)? AND/OR new architectures, topologies and algorithms required
* http://www.bigncomputing.org**chart data from www.top500.org
1st500th
Total
10x /3.5-4yrs = 85-90% CAGR
Increasing Parallelism1PF
1EF
6 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Cost and power of a supercomputer
YearPeak
PerformanceMachine
CostTotal Power
Consumption
2008 1PF $150M 2.5MW
2012 10PF $225M 5MW
2016 100PF $340M 10MW
2020 1000PF(1EF)
$500M 20MW
?Assumptions: Based on typical industry trends –(See, e.g., top500.org and green500.org)
– 10X performance / 4yrs (from top500 chart)– 10X performance costs 1.5X more– 10X performance consumes 2X more power
J. Kash Photonics Society Annual Meeting Nov 2010 and OWQ1 OFC 2011
7 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Evolution of Optical interconnects
WAN, MANmetro,long-haul
LANcampus, enterprise
Systemintra/inter-rack
Boardmodule-module
Modulechip-chip
Chipon-chip buses
1980’s 1990’s 2000’s
Time of Commercial Deployment (Copper Displacement):
Distance Multi-km 100’s m 10’s m < 1 m < 10 cm < 20 mm
> 2012
Increasing integration of Optics with decreasing cost, decreasing power, increasing density
TelecomDatacom
Computer -com
cards Card edge Card edge/on card
Module Si C or chipIntegration
BW * Distance: Optics >> Copper
On chip
8 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Why Optics?
LGA Socket
• Electrical Buses become increasingly difficult at high data rates (physics):• Increasing losses & cross-talk • Frequency resonant affects
• Optical data transmission is easier: • Much lower loss, esp. at higher data rates• Additional advantages include:
• Cable bulk, connector size, EMI…• Potential power savings
• KEY ADVANTAGE: BW * Distance > electrical• Optics trends for large servers and data centers are
following same trends as telecom network:• Longer links first• Short link optics requires tighter package integration:
• Higher BW closer to signal source• Changes the supplier/manufacturing paradigm
Card
Card
CPU
Bac
kpla
ne
Cross talk Freq dependent losses
Resonance effects
Copper
Optics
9 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation9
Bandwidth: the Bane of the Multicore Paradigm:
?Logic flops continue to scale faster than interconnect BW
• Constant Byte/Flop ratio with N cores (constant ?) means:Bandwidth(N-core) = N x Bandwidth(single core)
• 3Di (3D integration) will only exacerbate bottlenecks
Assumptions:• 3 GHz clock• ~ 3 IPC• 10 Gb/s I/O
• 1 B/Flop mem• 0.1 B/Flop data• 0.05 B/Flop I/O
Pins per chip
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
1 2 4 8 16 32 64 128
Number of Cores
Sig
nal +
Ref
eren
ce P
ins
Sig
nal +
Ref
eren
ce P
ins
M. Ritter Topical Workshop on Electronics for Particle Physics, Sept 2010
10 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation10
0
2000
4000
6000
8000
1000012000
14000
16000
18000
1 2 4 8 16 32 64 128
Number of Cores
Sig
nal +
Ref
eren
ce P
ins
Implications of BW Scaling:
Module Escape Bottleneck
Card Escape Bottleneck
Chip escape limit, 200?m pitch
Module escape, 1mm pitch
Card escape, 8 pair/mm(QCM w/8 Cores…)
Pins per chip
Sig
nal +
Ref
eren
ce P
ins
M. Ritter Topical Workshop on Electronics for Particle Physics, Sept 2010
11 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Total bandwidth, cost and power for optics in a machine
YearPeak
Performance(Bidi) Optical
BandwidthOptics Power Consumption
Optics Cost
2008 1PF0.012PB/s
(1.2x105Gb/s)0.012MW $2.4M
2012 10PF1PB/s
(107Gb/s)0.5MW $22M
2016 100PF20PB/sec
(2x108Gb/s)2MW $68M
20201000PF(1EF)
400PB/sec(4x109Gb/s)
8MW $200M
?Require >0.2Byte/FLOP I/O bandwidth, >0.2Byte/FLOP memory bandwidth– 2008 optics replaces electrical cables (0.012Byte/FLOP, 40mW/Gb/s)– 2012 optics replaces electrical backplane (0.1Byte/FLOP, 10% of power/cost)– 2016 optics replaces electrical PCB (0.2Byte/FLOP, 20% of power/cost)– 2020 optics on-chip (or to memory) (0.4Byte/FLOP, 40% of power/cost)
J. Kash Photonics Society Annual Meeting Nov 2010 and OWQ1 OFC 2011
12 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
1000
10000
100000
1000000
10000000
100000000
2004 2006 2008 2010 2012 2014 2016 2018 2020
Year
Num
ber
of O
ptic
al C
hann
els
HPC driving volume optics ? Computercom market
MareNostrum
ASCI Purple
Blue Waters*
WW volume in 2008
Single machine volumes similar to today’s WW parallel optics
Roadrunner2.5Gbps
10Gbps
5Gbps
?
* Expected Summer 2011 T. Dunning, NCSA, https://hub.vscse.org/resources/86/download/VSCSE_FutureofHPC_Jul10-2.ppt#265,1,Future of High Performance Computing
13 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Electronic Packet Switching
? Typical architecture (electronic switch
chips, interconnected by electrical or
optical links, in multi-stage networks) works well now---
– Scalable BW & application-optimized cost
• Multiple switches in parallel
– Modular building blocks • many identical switch chips & links)
? -- but challenging in the future– Switch chip throughput stresses the
hardest aspects of chip design• I/O & packaging
– Multi-stage networks will require multiple E-O-E conversions
• N-stage Exabyte/s network = N*Exabytes/s of costN*Exabytes/s of power
Central switch racks
J. Kash OFC tutorial 2008
By courtesy of Barcelona Supercomputing Center - www.bsc.es
14 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Next Gen Fiber Optics
Switch hub , optics on MCM
• ~Known (vendor) Technologies• Higher cost• Moderate Density
Potential Optics Technologies for Next Gen HPC – transition to OPCB?
Optical PCB Polymer waveguides
201820172016201520142013201220112010
300 PF20 PF
TSV Si carrier Optochips assembled
6.4mm x 10.4mm
2x12 PD
array
2x12 RX IC
2x12 LDD IC
2x12 VCSEL array
RXTXLDD RX
Si CarrierVCSEL
Lens Arrays
PD
Organic Carrier
PCBPolymer Waveguides
or Flex
To optical connector
TSV Si carrier Optochips assembled
6.4mm x 10.4mm
2x12 PD
array
2x12 RX IC
2x12 LDD IC
2x12 VCSEL array
RXTXLDD RX
Si CarrierVCSEL
Lens Arrays
PD
Organic Carrier
PCBPolymer Waveguides
or Flex
To optical connector
• Needs commercial ecosystem• Lower cost• Higher Density
20Gbps10Gbps 25-40Gbps
1 EFHPC Peak
Performance?
Optics Bitrate?
Volume commercial use lags HPC by ~4-5 years
IBM has technology expertise both in WGs and high bitrates
15 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Advantages of Polymer Waveguide Technologycompared to Parallel Fiber Optics
? Integrated mass manufacturing– Board, sheet, film level processing of optical interconnects– Lower assembly, waveguide jumper costs
– Costs for wide busses should scale better
? Simple assembly– Avoid fiber handling (integrated approach)
– Similar assembly procedures as for electrical components and boards (pick and place, etc.)
– Establish electrical and optical connections simultaneously (pick, place, reflow, etc.)– Avoid separate optical layer (if integrated with board)
? New or compact functionality supporting new architectures– Shuffles, Crossings, splitters, …– Enabler for multi-drop splitting, & complex re-routing that is expensive in fiber
? Higher density, waveguide pitch < 125 um (best future fiber pitch)– Higher bandwidth density, less signal layers…demonstrated 62.5um
? Cost– Reduced Optics module cost AND jumper/connector costs both important
– Possible Lower Maintenance costs
16 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Integrated packaging is more complex, requires close relationship with suppliers (IBM PERCS) Ideal candidate for PWG Packaging.
Heat Spreader for Optical DevicesCooling / Load Saddle for Optical Devices
Optical Transmitter/Receiver Devices 12 channel x 10 Gb/s28 pairs per Hub - (2,800+2,800) Gb/s of optical I/O BW
Heat Spreader over HUB ASIC
Strain Relief for Optical RibbonsTotal of 672 Fiber I/Os per Hub, 10 Gb/s each
Hub ASIC (Under Heat Spreader)
A.Benner, Future Directions in Packaging (FDIP) Workshop, EPEP Oct 2010
17 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Density of optical links
Courtesy of Avago Technologies
Optics Module and electrical connectorCard edge
~8X8mm, ~0.75mm pitch
~18x41mm 1.27mm pitch
Active cable, electrical at card edge
Courtesy of AvagoTechnologies
4x4 VCSELArray
4x4 PD
Array
4x4 VCSELArray
4x4 PD
Array
Optical at card edge
~60K fibers/ RACK
ROADRUNNER ~1PF)
~40K fibers / SYSTEM
PERCS >10PF
8@5Gbps/cable
48@10Gbps/cable
~5x3mm 0.2mm pitch
~10x25mm
~5X15mm
> 40x denser
18 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Optical waveguide interconnects:The Terabus project and related work
Dense Hybrid Integration: demonstrate a low-cost packaging approach compatible with conventional PCB manufacturing and surface-mount board assembly
Waveguide Lens ArrayWaveguide Lens ArraySLCSLC
CMOS ICCMOS ICCMOS IC
OE’sOE’sOE’sVCSELSLCSLCSLCSLC
OE’sVCSEL
CMOS ICCMOS IC
OE’sOE’sOE’s
Waveguide Lens ArrayWaveguide Lens Array
SLCSLC
CMOS ICCMOS ICCMOS IC
OE’sOE’sOE’sVCSELSLCSLCSLCSLC
OE’sVCSEL
CMOS ICCMOS IC
OE’sOE’sOE’s
CMOS ICVCSEL PD
Optochip
Optomodule
Optocard
Optomodule 2
Polymer waveguides
Waveguide Lens ArrayWaveguide Lens ArrayWaveguide Lens ArrayWaveguide Lens ArraySLCSLC
CMOS ICCMOS ICCMOS IC
OE’sOE’sOE’sVCSELSLCSLCSLCSLC
OE’sVCSEL
CMOS ICCMOS IC
OE’sOE’sOE’s
SLCSLC
CMOS ICCMOS ICCMOS IC
OE’sOE’sOE’sVCSELSLCSLCSLCSLC
OE’sVCSEL
CMOS ICCMOS IC
OE’sOE’sOE’s
Waveguide Lens ArrayWaveguide Lens ArrayWaveguide Lens ArrayWaveguide Lens Array
SLCSLC
CMOS ICCMOS ICCMOS IC
OE’sOE’sOE’sVCSELSLCSLCSLCSLC
OE’sVCSEL
CMOS ICCMOS IC
OE’sOE’sOE’s
SLCSLC
CMOS ICCMOS ICCMOS IC
OE’sOE’sOE’sVCSELSLCSLCSLCSLC
OE’sVCSEL
CMOS ICCMOS IC
OE’sOE’sOE’s
SLCSLC
CMOS ICCMOS ICCMOS IC
OE’sOE’sOE’sVCSELSLCSLCSLCSLC
OE’sVCSEL
CMOS ICCMOS IC
OE’sOE’sOE’s
CMOS ICVCSEL PD
Optochip
Optomodule
Optocard
Optomodule 2
Polymer waveguides
• Low-density, conventional electrical interface for power & control • High-density, wide and fast optical interfaces for data I/O? Much higher off-module bandwidth at low cost in $$ and power
Circuit Board w/ both electrical traces & optical waveguides
CPU OE XCVR
TransceiverOptochip
Other Chips
organic chip carrier
Future Vision: optically-enabled MCM’s Circa 2014-2016
< 10 FIT per channel
Reliability
2 Tbps/cm2
(on module)Density
25Gbps/channelDatarate
<$0.25/Gbps (TRx+ on-card optics)
Cost
<10mw/Gbps (EOE)
Power
19 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Outline
?System view of why optics is needed
?Potential OPCB Technologies for Next Generation HPCs
– OSA Designs
– OSA Assemblies
– Packaging
– Optical Component Characterization
20 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Optical Printed Circuit Boards
?IBM Research has invested heavily in the past 7+ years in Optical printed circuit board technology based on multi-mode polymer waveguides – Partially funded by the US Government (Terabus program)
?We believe this technology will be needed to provide the needed BW for future server generations, allow highly integrated electrical-optical links and provide a path to much lower cost optical links.
?We are highly interested in establishing a market eco-system that will provide a set of suppliers, standards and specifications and users for this technology.
21 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
y Offset (?m)
x O
ffse
t (?m
)
-80 -60 -40 -20 0 20 40 60 80
-80
-60
-40
-20
0
20
40
60
80
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
x 10-4
-80 -60 -40 -20 0 20 40 60 80
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
Offset (?m)
Cou
plin
g E
ffic
ienc
y (d
B)
BGA site for Optomodule
Waveguide Lens Array
35µm x 35µm
62.5µm pitch Module Attachment? BGA attachment process
? Alignment of OE lens array to waveguide lens array
Optocard Technology: Waveguides, Module Attachment and Tolerances
-50 -40 -30 -20 -10 0 10 20 30 40 50
-4.5
-4
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
Offset (? m)
Cou
plin
g E
ffic
ienc
y (d
B)
Lens Array
TRX IC
OE
SLC Carrier
FR4
Lens Array
TRX IC
OE
SLC Carrier
FR4
Tx: ±35 µm
Rx > ±65 µm
Optical coupling efficiency
22 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Lens Array
TRX IC
OESLC Carrier
FR4
Lens Array
TRX IC
OESLC Carrier
FR4
Optocard waveguides: Turning mirrors and Lens Array
BGA site for Optomodule
Waveguide Lens Array
?Integrated turning mirrors– TIR – laser ablation– Dense waveguide pitch
?Integrated 48-channel collimating lens array
– Provides 40mm alignment tolerance for Optomodule
channel 35, 40 not shown, in-coupling scattering
0.00
0.50
1.00
1.50
2.00
2.50
0 10 20 30 40 50
Channel Number
Bo
ard
Lo
ss (d
B)
Median : 1.6Stdev: 0.1
1.6 dB average loss?0.9dB for 7.5cm WG @980nm?~0.7dB for mirror/lens assembly
Waveguide/Mirror Uniformity
48-channel Waveguide mirror array
waveguide cores on 62.5um pitch
48-channel Waveguide mirror array
waveguide cores on 62.5um pitchTIR mirrors
23 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Waveguide Connectors: Passive alignment with optical precision
MT pins
Alignmentstuds
Coppermarkers
waveguides
Alignmentslots
PCB
MT ferrule aligned by copper markers Positioned MT ferrule to polymer waveguides
Connector interface 12 waveguides Alignment marker
Top FR4 stack (with electrical lines)
Polymer waveguide layer
Bottom FR4 stack
24 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Terabus Transceivers – 985nm and 850nm built
?Optochip: Single-chip CMOS transceiver IC with flip-chip attached optoelectronic arrays
?985nm, substrate emitting OEs
Optomodule
Waveguide Lens Array
Optocard
SLCSLC
Transceiver Optochip
CMOS ICCMOS ICCMOS IC
OE’sOE’sOE’sVCSEL OE’sOE’sOE’sPDOptomodule
Waveguide Lens Array
Optocard
Waveguide Lens ArrayWaveguide Lens Array
Optocard
SLCSLCSLCSLC
Transceiver Optochip
CMOS ICCMOS ICCMOS IC
OE’sOE’sOE’sVCSEL OE’sOE’sOE’sPD
CMOS ICCMOS ICCMOS IC
OE’sOE’sOE’sVCSEL OE’sOE’sOE’sPD
CMOS ICCMOS ICCMOS IC
OE’sOE’sOE’sVCSEL OE’sOE’sOE’sPD
?Optochip: Si carrier platform for heterogeneous integration of OEs and ICs
?Electrical and Optical vias in Si carrier
Chip-to-chip optical interconnect on a PCB using 985nm transceivers (non-standard wavelength)
Chip-to-chip optical interconnect on a PCB using 850nm wavelength transceivers (industry-standard wavelength)
Optochip
?Optomodule: High-speed, high-density organic carrier?Extendible to optically enabled MCM (OE-MCM)
?Optocard: PCB with integrated polymer waveguides?Replace complex electrical PCB with simpler electrical PCB (power and control), plus
waveguides
SLC Substrate
SiCarrier
LDD VCSEL PD TIA
SLC
SiCarrier
LDD VCSEL PD TIA SC
LDD VCSEL PD TIA
Lens ArrayLens ArrayLens Array
FR4 Substrate
SLC Substrate
SiCarrier
LDD VCSEL PD TIA
CoreEZ
SiCarrier
LDD VCSEL PD TIA SC
LDD VCSEL PD TIA
Lens ArrayLens ArrayLens Array
FR4 Substrate
Lens ArrayLens ArrayLens Array
FR4 SubstrateFR4 Substrate
SLC Substrate
SiCarrier
LDD VCSEL PD TIA
SLC
SiCarrier
LDD VCSEL PD TIA SC
LDD VCSEL PD TIA
SLC Substrate
SiCarrier
LDD VCSEL PD TIA
SLC
SiCarrier
LDD VCSEL PD TIA SC
LDD VCSEL PD TIA
Lens ArrayLens ArrayLens Array
FR4 Substrate
SLC Substrate
SiCarrier
LDD VCSEL PD TIA
CoreEZ
SiCarrier
LDD VCSEL PD
Lens ArrayLens ArrayLens Array
FR4 Substrate
SLC Substrate
SiCarrier
LDD VCSEL PD TIA
CoreEZ
SiCarrier
LDD VCSEL PD TIA SC
LDD VCSEL PD TIA
Lens ArrayLens ArrayLens Array
FR4 Substrate
Lens ArrayLens Array
TIA SC
LDD VCSEL PD TIA
Lens ArrayLens ArrayLens Array
FR4 Substrate
Lens ArrayLens ArrayLens Array
FR4 SubstrateFR4 Substrate
25 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Full Terabus Link (985-nm): 2 Transceiver Optomodules on Optocard
16 Channels TRX1 ? TRX2 at 10Gb/s + 16 Channels TRX1 ? TRX2 at 10Gb/s
TRX1:
16TX + 16RX
TRX2:
16TX + 16RX
4x4 VCSELArray
4x4 PD
Array
26 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Terabus 850 nm Transceiver Optochip Assembly
? Silicon Carrier provides dense high-speed wiring, mechanical support, and optical I/O through holes etched in the carrier
? Heterogeneous integration of ICs and OEs through dense arrays of solder “microbumps”
– IC pads: ?= 35?m, pitch = 50?m– OE pads: ?= 35?m, pitch = 100?m– ~1um Au-plating on pads
? Optochip assembly: four sequential flip-chip soldering processes– Suss FC-150 flip-chip bonder– AuSn solder pre-deposited on ICs, VCSEL & PD arrays
– Reflow solder at about 320 °C
Silicon Carrier
RX ICLDD IC
High-speed probe pads
VCSEL arrayPD array
LDD IC RX IC
VCSEL array PD array
TSV Si carrier
27 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Assembled Terabus 850-nm Optomodule(Optochip on CoreEZ)
First row of solder joins visible beneath the Optochip
850-nm Optochip demonstrated? 300Gb/s bidirectional aggregate data rate
TX:15Gb/sRX:12.5Gb/s
28 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
VCSEL Transmitters and Receivers can achieve 2015 metrics for density, bitrate and power ? 90-nm IBM CMOS-Driven VCSEL Transmitters and Compatible Receivers
– Power and Speed Records
28
2.8 pJ/bit0.7 pJ/bit
20Gb/s
1.9 pJ/bit
29Gb/s 32Gb/s20Gb/s
1.75 pJ/bit
VCSEL Transmitters
Compatible Receivers
2.9 pJ/bit 3.5 pJ/bit 6.7 pJ/bit
15Gb/s 17.5Gb/s 20Gb/s
IBM technology expertise in high bitrate transceivers
29 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Development of VCSELs for >25 Gb/s links –collaborations with OE vendors
26Gb/s 30Gb/s
Joint work with Finisar AOC
Joint work with Emcore Corp
20Gb/s 25Gb/s
8mA700mVpp
*R. Johnson and D. M. Kuchta, “30Gb/s directly modulated VCSELs,” CLEO 2008
*N. Y. Li et al., “High-Performance 850 nm VCSELs and Photodetector Arrays for 25 Gb/s Parallel Optical Interconnects,” OFC 2010.*N. Y. Li et al., “Development of High-Speed VCSELs Beyond 10 Gb/s at Emcore,” Photonics West 2010.
6mA375mVpp
30 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Embedded Waveguide Technology: 120 Gb/s Board-to-Board Optical Link Demonstrator
? Embedded polymer waveguides (12 channels)
? Passive alignment of MT standard based connectors
? MT interface as standard interface for WG, fiber bundles/optical flexes and transceivers
? Pluggable TX/RX module (butt coupling)
Optical TX/RX board as building block Complete 12x10 Gb/s link demonstrator
12 embeddedwaveguides
EO modulMT
interface
10 Gb/s 10 Gb/s
Eye diagrams for 2 channels at 10 Gb/s
IBM technology expertise in high bitrate optical PWG Link Prototype builds
31 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Field Replacable Optics – OE Carrier/LGA , Dual Layer PWG
?OE Carrier: Wafer based micro-optic assemblies, organic substrate for electrical interconnect (low cost). Removable carrier, passive alignment.?PCB / Waveguide Board: PCB with dual layer buried polymer waveguides,
integrated waveguide lens arrays.?LGA Assembly: Low force LGA, course & fine alignment means.?Optical Components: 1x12 arrays : 850nm VCSEL and photodiode Arrays (10Gb/s)
VCSEL arrayPD array
LDDTIA
WG arrays with mirrorsLens arrays
Backplane Connector (TRL)
Organic CarrierLGA
Heat SpreaderCarrier
PCB
LGA
IBM technology expertise in field replaceable optical TRx packaging
Libsch, F.R. et. al., “ MCM LGA packaging for Optical I/O Passively Aligned to Dual Layer Polymer Waveguides”,IEEE Electronic Components and Technology Conference (ECTC), 2006
32 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Waveguide-on-flex cables:192 Channel flexible waveguide optical backplane
8 waveguide flex sheets, 192 waveguides, 8 connectors
4 connectors, 48 waveguides each
?Multi-layer waveguide optical connector?Based on passive alignment?Basic building block for optical pcb backplane technology
Optical L-Links
Optical D-Links
33 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
48-Channel-to-4x12-Channel Waveguide Flex Fan-Out
12 WGswith 250 ?m pitch
48 WGswith 62.5 ?m pitch
Light incoupling
Waveguide cross-section
34 November 2011IBM INTERNAL ONLY © 2009 IBM Corporation
Summary and Questions for Discussion?As shown, optical polymer waveguide interconnect technology
are a candidate for high performance computer optical interconnects.
?IBM is working with other system houses to define commonality, drive volumes up, and provide for lower cost to both system and component vendors.
?IBM is not likely to build this technology for itself, just as we currently do not manufacture PCBs and organic build-up technologies or optical transceivers
• IBM has developed research-level technologies for all aspects of the technology
• Commercialization of waveguide-on-card manufacturing would require working with a commercial PCB vendors and a waveguide materials supplier, as well as a manufacturer of the optical transceivers
?What role do vendors (yourself) envision for yourself in that ecosystem? Comments welcomed.