Embedded Polymer Waveguide to Optical Fiber

InterconnectsCreating the Optimal Link

Dr. Blanca Ruiz, Marika Immonen, Dr. Andres Ferrer, Christian Gsell, Dr. Peter

Cristea

CTI – Corporate Technology & Innovation

Reichle & De Massari AG

Wetzikon, Switzerland

Reichle & De Massari AG

LATAM

NA

META

APAC

Europe

Privately Owned CompanyAnnual Revenue 2017 : 230 MCHFEmployees: >900Headquarters : Switzerland

Reichle & De Massari AG

Complete cabling solutions

for high-end communication

networks in the fields of:

Office Cabling (LAN)

Data Center

Public Networks

Connectivity and cabling (Fiber Optic and Electric)

Cable management

Infrastructure Monitoring

Complete

layer 1

portfolio

On-Board Optics & Collaboration Project RDM-TTM

4

Addressed WG

• Polymer multimode waveguides

with square cross-section.

• Arrays of 12 waveguides per group

• MPO grid compatible

Target Performance

• Connector loss ≤ 1dB per channel

• Stable IL values for at least 10 mating cycles

• Stable for subsequent electronics soldering

process

Main Challenges

• Alignment

• Different materials (core refraction index,

hardness)

• Mechanical Stability

• Product with optical layers (Line Card)

• 20 electrical layers with 1 optical layer

• Dimension (WxH): 277 x 312 mm

(10”x12”)

• Material: EMC EM-285 HF

• Thickness: 2.8mm (+/- 0.300)mm

On Board Optics – Interface to MT

5

Multimode WaveguideCore dimension: 50 x 50 µmStep index polymer coreYoung’s Modulus 2-4

Multimode Fiber (OM4)Core diameter 50 µmGraded index glass coreYoung’s Modulus 50-90

λ = 850 nm

• Fiber eccentricity to < 3 µm

• Reference is center point between MT pins

• Waveguide position is arbitrary and must be

referenced to rigid fiber array via MT pins

Addressed WG

• Polymer multimode

waveguides with square

cross-section.

• Arrays of 12 waveguides

per group

• MPO grid compatible

Mechanical stability an issue for repeated mattings

Alignment Tolerance for Rectangular Cross Section WG

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

-20 -15 -10 -5 0 5 10 15 20Tota

l In

sert

ion

Lo

ss p

er

Co

nn

ect

or

(dB

)

Displacement (µm)

Effect of WG-Fiber Missalignment

Rectangular CrossSection WG

R&M Specs

• Excess loss < 0.5 dB in all channels

• Mating cycles > 20

• Transferable process for assembly

house

• Connector able to withstand

soldering

Requires

• Lateral Alignment Tolerance < 5 µm

• XYZ translations

• 3 Angle tolerances accumulate

• Fiber array eccentricity 3 µm

• WG array eccentricity 3 µm

• Physical Contact

• Heat resistance materials

Very Challenging for

Passive Alignment!

• Cross section mismatch penalty:

~ 0.5 dB

• WG end face quality factors: polish,

perpendicularity

R&M Approach

▪ Active alignment of reference pins to board

• 6 degrees of freedom

alignment

• Pins cured into position

FR4

WG core MT pin

▪ Connector Design

Standard force for an MPO connector is ~ 2N per fiber

– Modified adapter

protects waveguide front face from plastic deformation or

fractures within waveguide core due to stress

Equalizes the ferrule force upon the edge of the board

Controls contact angle

Ensures physical contact Patent Pending

Next steps:

External footprint reduction

Further automation of assembly

▪ Assembly Process

– Tools and process developed at R&M

– Transferable to assembly house

Passive Waveguide Backplane Evaluation Card

Optical port

(12-ch…48-ch)

Optical port

Optical portOptical port

Optical electrical PCB

Parallel waveguides

Pluggable MPO interface

Optical port

(12-ch…48-ch)

Ch1 Ch2 Ch3 Ch4 Ch5 Ch6

Results

• Measured with EF

• Referenced vs single

channel basis

• Includes losses of 1

MPO cable

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9 10 11 12

TIL

(dB

)

Ch number

Effect of mating cycles (1 to 100)Mating Nr 0Mating nr 1Mating nr 2Mating nr 3Mating nr 4Mating nr 5Mating nr 6Mating nr 7Mating nr 8Mating nr 9Mating nr 10Mating nr 11Mating nr 12Mating nr 13Mating nr 14Mating nr 15Mating nr 16Mating nr 17Mating nr 18Mating nr 19Mating nr 20Mating nr 25Mating nr 30Mating nr 35Mating nr 40Mating nr 50Mating nr 60Mating nr 70Mating nr 80Mating nr 90Mating nr 100

0

0.2

0.4

0.6

0.8

1

1 2 3 4 5 6 7 8 9 10 11 12

Inse

rtio

n L

oss

(d

B)

Channel

Connector Losses vs Reference

Average loss = 0.57 dB

σ = 0.14 dB

Embedded Waveguide PCBs for On-Board Optics

▪ Passive backplane with 60 polymer waveguides in port/to/port 12-ch links

▪ All WG channels terminated by RdM’sWG connectors

▪ Waveguides embedded part of PCB stack

▪ Pluggable connector interface

Edge connector (1x12-ch) Edge connector (1x12-ch)

Waveguides

(12-ch)

Waveguides (12-channels)

Evaluation Platform : Passive Waveguide Backplane PCB

Waveguides

(12-ch)

Demo booth #334

Current Work in Dual-Layer Waveguides

Development of multilayer (dual-layer) OPCBs

a b c e

f g h i

MM Dual-WG OPCB development

First dual-layer units complete

Varying core sizes: width 20’ 35’ 50’ 60 µmx height 45-90µm

Excellent layer-to-layer registration < +/-5µm

2L OPCB fabrication in 16”x20” production panel

Proprietary and Confidential

Dual layer WG construction

13

PhoxDem09.04 Application Demonstrator

Photonic Midplane with E-WG Shuffle Routing

38

.00

00

15

0.3

00

0

12

3.8

71

3

Dual layer WG connector IO

Perfect shuffle WG routing

Proprietary and Confidential

PhoxDem09.04MPX – 18L+2Opt Embedded WGs

Optical waveguide

shuffle network

Application Prototype:Optical/Electrical Midplane 18L+ 2 Opt WGs

14

Dual layer waveguide

structure

Waveguides revealed with multilevel recess cavities

to visualize embedded WGs in 18L stack

L1-L9

L1-L18

L10-L18

OPT-1

OPT-2

OPT-1

OPT-2

Shuffle Midplane with Polymer Routing Network

▪ Integrated photonic layers part of internal PCB layers▪ Registration between optical layers < 5µm (500µm vertical pitch)

F G

E

CB

A

CA

D

E

D

I

IF

RDM Connector and Process is compatible with double

layer and potentially with SM waveguides

WIP

Summary

16

• R&M has designed, produced and tested an MT compatible connector

for polymer waveguides on rigid PCB

• We demonstrated an average loss of 0.57 dB for the DUT including one

MPO cable

• We demonstrated 100+ connection cycles without degradation of the

optical performance

• Our connector places minimum requirement on the referencing of the

waveguides within the OPCB

• The RDM on board connector and process is compatible with a dual-

layer OPCB

• Our active process is transferable to assembly and large scale

production

Multi Fiber Connector

for On-Board Optics

Contact Information

Marika ImmonenManager, Optical Interconnects

Advanced Development – Corporate Technology

TTM Technologies

Marika.Immonen@ttmtech.com.hk

Mobile: +358 50 599 3136

Dr. Blanca RuizSenior R&D, OPCB Project Leader

Corporate Technology & Innovation

Reichle & De Massari

blanca.ruiz@rdm.com

Phone: +41 44 933 85 23

Access – Fiber to the Board