Optical Interconnect Project

Status Update and Plan

M.Immonen/ TTM and Brice Achkir/ Cisco

Sep 15, 2011

1

Content

• Need and Rationale

• Objectives (Project Level)

• Project Test Vehicles

• Test Vehicle 1

• Description

• Goals and Deliveries

• Testing Plan

• Resources

• Schedule

• Scope Re-Check and Refinement Needs

2

The Need – System Level Overview

Joel Goergen/Cisco: FR-4 Circuit Board Technology: An Introduction to Fabrication

Issues in High Speed Channels. 03’2011

What problem are we solving?

High-Speed Channel SR

(27”..32”)?

High-Speed Channel SR (<12”)?

Bandwidth off-PKG/Module?

Bandwidth off-Card?

Front-panel density? NEXT Near-end crosstalk

FEXT Far-end crosstalk

Optics vs. Copper Rationale

4

Bandwidth Density

Gbps/mm2

mW/Gbps=pJ/bit

Objectives (Project Level)

1. Understanding on performance benefits and limitations

using optical fibers and polymer waveguides for intra-

system interconnects (Reach < 1-2 m)

2. Demonstrate backplane architecture(s) that shows cost or

performance improvements obtained by using optical links

3. Focus on optical fiber/WG link characteristics, connectivity

options, end-to-end link implementations and reliability of

the same

4. Showcasing technology options and cost competitiveness

to demonstrate optical connectivity using practical hybrid

fiber and polymer waveguide solutions that exist today

5. Use ”Black-box” approach, standardized components and

interfaces, be protocol-agnostic, focus on practical

solutions

5

Project Test Vehicle Designs

1st TV: Verification Test Vehicle (TV1)

• Board Backplane with connector interfaces

• Used to verify design parameters and connectivity options for TV2

• Basic TV, basic performance and reliability testing by the team

• Currently 3 available WG technologies to build TV1

• Specification and design must fit all WG technologies

• Design to include multiple WG components fitting realistic application targets

• Connector interfaces that can be used for performance testing and for

interfacing by OEMs and others to evaluate specific applications

• May want to include at least one daughter card with some kind of function on it

to test the backplane interface (no need for daughter card since the wg willl be

compared to copper directly)

• Must allow application/company specific tests and interoperability testing

2nd TV: Demonstration Test Vehicle (TV2)

• Backplane with N Line Card(s) and M Switch Card(s)

• More difficult TV, Enhanced testing by the team

• Expanded specification challenging the technologies

• Connector interfaces that can be used for performance testing and for

interfacing by OEMs and others to evaluate specific applications

• Must allow application/company specific tests and interoperability testing

6

TV1 Goals and Deliverables

1. Design and test multimode optical waveguides and high-

speed copper lines of varying length on a common passive

PCB test bed. Comparison provided on 1-3 base materials

representing standard-loss (FR408HR) mid-loss (HE-679G)

and ultra-low loss (R3003). Link lengths up to 8” (wgs)

2. Demonstrate high-density multichannel optical waveguide

links with low loss fabricated on standard size PCBs (single

layer, top surface, WG loss 0.05 dB/cm, board 12”x18”)

3. Design and test waveguide routing components needed to

realize practical Optical Backplane/Card interconnect

circuitries incl. straight, bend and crossing components

4. Characterize and compare end-to-end optical and copper

links on key link metrics – link loss, BW density, power,

signal integrity up to 25 Gbps

7

TV1 Goals and Deliverables

5. Characterize polymer waveguides functional parameters –

optical loss, bend loss, cross-over loss, waveguide NA and

index contrast, and coupling loss with MMFs at 850 nm

6. Demonstrate robust low-loss (< 2.5 dB) connectivity options

to interface polymer waveguides on-board (Chip-to-WG,

board-to-BP). Multiple optical connector options in TV1

7. Demonstrate unique polymer waveguide characteristics

and benefits over fiber for short reach (SR < 12”)

8. Provide robust and scalable polymer waveguide and

fiber/waveguide building blocks for TV2 functional

demonstrator

9. Provide end-use application and specification for TV2

optical interconnect backplane competitive to copper

solution

8

This Project will NOT…

• Evaluate polymer waveguide processing methods, address/solve

manufacturability or production scale up issues

• Develop optical engines or transceiver subassemblies

• Primarily focus on off-package optical connectivity. Use of

waveguides in PKG or for off-package routings may be addressed

• Study architectural benefits obtainable using polymer

interconnects. Novel photonic system architectures vs. more

efficient implementations of traditional designs

• Use communication architectures other than point-to-point

• Use transceivers limited to mount at the card edge

• Evaluate or use higher order modulation schemes in coding

• Build application specific prototypes (Applies TV1)

• Use solutions based on WDM or single mode fibers/WGs

• Primary interest: 850 nm (<1µm), exclude 1.3 µm and 1.55 µm

• Need for multi-protocol module support

• Provide development for chip-level photonic networks/interconn’s 9

Test Vehicle 1 Layout (Optical)

Nx12 WGs, Straight; Length L2

WG

channel loss

(Ref.)

WG end face

coupling loss

Link loss with

connectors

(multiple

connector options

and link lengths)

Connector

coupling loss

In-plane launch BP connector with

90-deg turn Right angle launch MT Edge/Mid-board

90-deg up turn in WGs

Waveguides

Nx 12 WGs, Straight; L2

12 WGs, Straight; L1

12 WGs, Straight; L1 12 WGs, Straight; L1

12 WGs, Straight; Length L2

12 WGs, Straight; L1

(multiple

connector options)

Crossings 90-deg bends, Cascading bends

BACKPLANE

.

.

.

.

.

.

Nx12 WGs, Straight; Length L1

12 WGs, Straight; Length L2

Point-to-point TV for Multimode based λ = 850 nm VCSELs

provided via externally launched test source and fiber-optic ribbons

Notes:

- All waveguide arrays are on board surface

- Layout is to be finalized in accordance with actual board design

- Schematic illustration, sizes not to scale, may not include all design variations

- Fiber ribbon links not shown

- Electrical connectors or ref. lanes not shown 10

Test Vehicle 1 Materials and Connections

11

• Laminates

• Isola FR408 Dk< 3.64 Df < 0.013

• Hitachi MCL-HE-679G

• Rogers R3003 Dk 3.9-4.1 Df 0.0013

• Optical waveguide materials

• GuideLink™ / OIL; NA=0.2-0.32

• LightLink™/ Dow EM; NA=0.26-0.31

• Proprietary/ API; NA=0.2-0.37

• OE4140/41/ Dow Corning; NA=0.2x

• Connectors and connectivities

• FCI Optical BP connector (90-turn)

• OIL Optical BP connector (90-turn)

• Mirror I/Os on waveguides (90-turn)

• WG Edge connector

• Molex Expanded beam MT (lensed)

WGs with Mirrors Wgs on PCB (top)

BP 90-turn Edge conn. BP 90-turn Expanded beam

(lensed)

WGs Flex

Waveguide Design Features

12

1 2

3

4

1

12

1. Straight waveguide array sets (N=12

channels)

• Fixed width w=50µm

• Fixed center-to-center spacing: 250 µm

• Varying length: L1=15 cm; L2=30 cm

2. Nested sets of 90° bends

• Varying ROC (R=RS…RN) with fixed width

E.g. R= 5’ … 20 mm, w= 50 µm

• Varying ROC Varying waveguide widths

E.g. w= 35‘ 50‘ 70 µm

• Straight section lin and lout E.g. 10 mm

3. Staggered cascaded bend

• Mode mismatch loss between segments of

different RoCs

4. Long waveguide loop (Not needed)

5. Over crossings

1

12 250

50

50

Test Vehicle 1 Layout (Electrical)

Layer Name

1 Top

2 P

3 G

4 S

5 G

6 P

7 P

8 G

9 S

10 G

Layer Name

11 G

12 P

13 Bottom

LS – Low Speed

HS – High Speed

Proposed Stackup:

G-S-G Config

Proposed Stackup:

G-S-S-G Config

Layer Name

1 Top

2 P

3 G

4 S - LS

5 S - HS

6 G

7 P

8 G

9 S – LS

10 S – GS

Layer Name

11 G

12 P

13 Bottom

13

Testing Plan Update

14

Fabricate Boards

As-built Testing

Electrical testing 1

Optical Loss:

Waveguide channel loss, material loss, bend losses, cross-over loss, coupling loss to MMFs,

loss post-lamination

Refractive index & NA

(NF/ Fiber Analyser)

Physical Xsect

Connectors: IL, RL, misalignment tolerance,

mate/unmate

With connectors

Comm. Measurements Copper Links: IL, Eye,

BER

Comm. Measurements: Optical Links

OTDR

Reliab.test

Link parts. System test In-situ

monitoring of IL at established read

points Link BER,

before/after

Waveguide loss and refractive index

stability

6x 260C

Reflow

Phase I tests to ensure waveguides and interfaces

are practical and they meet the specification

Optical Loss Measurements

15

Optical Tests——WG Transmission loss

nm850

L2

L1

Optical detector

In-coupling fiber Multimode 50µm NA=0.2

Out-coupling fiber MMF 62.5 µm NA=0.28

(Core > WG)

Optical Source

1 2T (IL IL ) /(L1 L2) (dB/cm)L

P10

P

out

in

IL Log

Link Evaluations

16 ©HDP User Group International, Inc.

Proprietary

TX +

Fiber

patch

cord

RX +

Fiber

patch

cord TP1 TP3

TP2

LINK 1: TX – OF – Conn 1 – Waveguide – Conn 2 – OF – RX

WG Ref.

(Unconnectorized)

MT Edge

MT Mid

board

MTP BP

(design example) MTP male

connector to 12

individual FC/APC

connectors, bare

ribbon to 900um

buffered, 0.45m

breakout, 2m total

length

MTP male to 12 FC/APC,

bare, 2m

BACKPLANE

Waveguide to

Fiber coupling

evaluations

Waveguide Channel

Scope and Deliveries – Re-Check

• Are we fine with objectives Project level?

• Are TV1 goals and deliverables realizable?

• Are deliverables sufficient to compensate the

effort?

• Novelty perspectives? Goals vs. previous work?

17

Schedule

Project Task Who Complete Planned

Completion

Phase I - Verification TV (TV1)

Design complete NGC 10/11

Copper and optical simulation complete Cisco, Dow Corning 10/11

Laminate materials received Hitachi, Isola, Rogers 11/11

PCB Board fabrication complete TTM 12/11

Electrical testing 1 TTM/Cisco 12/11

Waveguide layer fabrication complete OIL, Dow, API 01/12

Waveguide optical measurements complete Xyratex, OIL, API,

Fujitsu, EOS

02/12

Waveguide physical analysis complete TTM 02/12

Optical connectors received FCi, OIL, Molex 02/12

HS connectors received TBD 02/12

Optical connector assembly complete Source 03/12

HS connector assembly complete Source 03/12

Comm. measurements - Copper & Optical Links Cisco, Huawei, Celestica 04/12

Failure analysis complete TTM 05/12

Phase I report complete Team 07/12

Phase II - Demonstration TV (TV2)

18

Resources and Support

Resource VOLUNTEER (2011-08-30)

DESIGN AND MFG SERVICES

--- Design TV1 Backplane (Electrical and Optical) NGC

--- Waveguide Simulation Dow Corning

--- Copper Simulation Cisco

--- Fabricate Backplane TTM

--- Fabricate Optical Waveguide Layer & Provide material OIL, APi, Dow Corning

--- Optical Connector Assembly Source

--- HS Connector Assembly Source

MATERIALS AND COMPONENTS

--- Laminate Materials Rogers, Hitachi, Isola

--- Optical Connectors FCI, OIL, Molex?

--- High-speed electrical connectors Tyco, Amphenol, Molex – TBD

TESTING

--- Optical Waveguide Characterization OIL, Xyratex, API, Fujitsu

--- Comm. Measurements (Electrical & optical links) Cisco, Huawei, Celestica

--- Physical & FA TTM

19

PC

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Contributing Members and Non-Members (Fabricators, testers, materials, components)

Rogers

Hitachi Isola

Guangdong Shengyi

Advanced Photonics

Dow EM Dow Corning

Optical Interlinks

Reflex Photonics

TTM

FCI

Molex

Tyco Electronics

Amphenol

Flextronics

Northropp Grumman

Celestica

Compass EOS

Cisco

Fujitsu

Huawei

Xyratex

Participants (Members/Non-members)

Project

Supply Chain

Total: 35 companies (11 non-members)

20 P

CB

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Other Members in Team

National Semicond.

Viasystems

Alcatel-Lucent

Boeing

Ericsson

IBM

Juniper

Oracle

Philips

Conpart

ITEQ

Nabaltec

Nihon Superior

Black = HDPUG Member

Brown= Non-HDPUG Member

Definition Stage Non-Member Participants

21

Red = Non-HDPUG Member, not offered to volunteer resources

Total: 20 companies (20 non-members)

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Non-members who have not volunteered to provide resources

Calumet

Adamant

Albemarle

Atotech

Chiral Photonics

Diamond USA

AMD

Nokia Siemens Network

Hakusan Mnf

ITRI

MMM

Opticomp

Optical Switch

Park Electrochem.

Promex

Purdue Univ.

Samsung

Triformix

UTA

Vario-Optics

END

22

Optical Interconnection Model

23

Interconnection Model

1 1

2

Terminology

1. Chip-to-Waveguide Connector

2. On-Card Link

3. Card-to-Backplane Connector

4. Card-to-Card Link

5. Chip-to-Chip/Module Link

6. Logic Chip (PU, SU, FPGA)

7. Optical Transceiver (E/O/E)

8. Card (Line Card, Switch Card)

9. Backplane/ Midplane

10. Chip/Module

8

6 6

4

3

9

CA

RD

CA

RD

BACKPLANE

3

5

2

4

2

2

5 7

10

Fiber

Waveguide

Optical Interconnection Model

24

Interconnection Model

1 1

2

Terminology

1. Chip-to-Waveguide Connector

2. On-Card Link

3. Card-to-Backplane Connector

4. Card-to-Card Link

5. Chip-to-Chip/Module Link

6. Logic Chip (PU, SU, FPGA)

7. Optical Transceiver (E/O/E)

8. Card (Line Card, Switch Card)

9. Backplane/ Midplane

10. Chip/Module

8

6 6

4

3

9

CA

RD

CA

RD

BACKPLANE

3

5

2

4

2

2

5 7

10

Fiber

Waveguide

TV 1