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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
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
Mobile: +358 50 599 3136
Dr. Blanca RuizSenior R&D, OPCB Project Leader
Corporate Technology & Innovation
Reichle & De Massari
Phone: +41 44 933 85 23