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The future of optical fibre in data centers
Dr. Rick Pimpinella, Panduit Fellow
Optical Fibre Research
Member IEEE
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© 2018 Panduit Corp. All Rights Reserved.
MMF will continue to provide 3 major benefits
1. Lower cost than single-mode data communicationsa) MM VCSEL transceivers are less expensive than SM DFB laser transceivers
b) Relaxed manufacturing tolerances
c) Lower transceiver power consumption
2. More robust connectivitya) Components more tolerant to dirt and dust
b) Connectors do not require high return loss
c) No multipath interference
d) More forgiving to long-term connector degradation
3. Meets Data Centre & Enterprise reach & bandwidth requirementsa) For foreseeable future (> 15 years)
Multimode fibre will be the main focus of this presentation
VCSEL DFB
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Technical Overview
• Differences between MMF types
‒ Fundamental properties of MMF
‒ Optical channel penalties
• Future applications for MMF in the DC
‒ Parallel optics vs. SWDM
• Single-mode fibre & application
• Looking forward more than 15 years out
‒ Future proofing your network
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MN 0.3dB
3.02dB
1.5dB (connectors)
+ 1.1dB (fibre)
2.6dB
0.8dB
MPN 0.07dB
RIN 0.17dB
Correction Noise 0.36dB0.90dB
Inter-Symbol Interference
Due to transmitter jitter
& fibre dispersion
Power
Budget
(dB)
IL
Margin
8
7
6
5
4
3
2
1
0
Polarization Noise 0dB
Reflection Noise 0dB
ISI
10 GbE Optical Power Budget for MMF
IL is independent of data rate
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Channel insertion lossFor VCSEL Transmission Over MMF
0
100
200
300
400
500
600
1GbE 10GbE 40GbE 100GbE 128GbE
Max
imu
m R
each
(m
)
Data Rate
Multimode Channel Reach & Channel IL
Fibre IL = 1.93 dB
Fibre IL = 1.05 dB
Fibre IL = 0.52 dB
Fibre IL = 0.35 dB
Fibre IL = 0.30 dB
Bit RateReach
(m)Fibre Type
1 GbE 550 OM2
10 GbE 300 OM3
40 GbE 150 OM4
100 GbE 100 OM4/OM5
128 GbE 85 OM4/OM5
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3.25 dB Inter-Symbol Interference
Due to fibre dispersion effects
1.5 dB (connectors)
+ 0.4 dB (fibre)
1.9 dB
Power
Budget
(dB)
IL
8
7
6
5
4
3
2
1
0
ISI
100G BASE-SR4 Optical Power Budget For MMF
1.85 dB Transmitter Jitter5.1 dB
ISI is the limiting power penalty in high-speed links
Modal Noise
Mode Partition Noise
Relative Intensity Noise
Correction Noise
1.2 dB
Reflection Noise
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Multimode Fibre ModesA pulse of light splits and travels along different optical paths called “modes”
3 of 380 possible modes (optical paths)
Caustic Surfaces
Skew Mode
Fiber Core
Meridian Plane Through Optic Axis
Fiber Core
a
Fiber Core
Fibre Core
Cladding
RR = 25 microns
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1.44
1.445
1.45
1.455
1.46
1.465
1.47
-35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35
1.44
1.445
1.45
1.455
1.46
1.465
1.47
-35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35
n
Manufacturing Variation in Refractive Index Profile
1.44
1.47
1.44
1.47
n
r
0R=25mm
n1
n2
Core
Cladding
D = 1.02 %
n
cv
2
1
2
2
2
1
2n
nn D
2/1
1 21
D
a
R
rnrn
where,
a ~ 2 for 850 nm250/50 probability
1
2
1.44
1.47
1.44
1.47
n
r
0R=25mm
n1
n2
Core
Cladding
D = 1.02 %
n
cv
2
1
2
2
2
1
2n
nn D
2/1
1 21
D
a
R
rnrn
where,
a ~ 2 for 850 nm2
a2 >a0
a1 <a0
R = 25 mm
n1
R
a0
where, c = speed of light in vacuum
= 299,792,458 meters per second
n2
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ISI Contribution No. 1 – Modal Dispersion
Input Data
Multimode fiber core
Pulse broadening
Output bits
Two sequential data bits “Symbols” Modal dispersion Inter-symbol Interference
2 data bits
2 a1 > a0
t
t+Dt
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IEEE Link Model Calculated Channel Reach For Cisco’s 40G BiDi
50
60
70
80
90
100
110
120
130
140
150
820 830 840 850 860 870 880 890 900 910 920 930 940 950
Rea
ch
(m
)
Wavelength (nm)
Panduit’s Signature Core™ OM4+ fibre
l1 l2
Reach Requirement
Standard OM4 multimode fibre
1
2
• Reaches using Measured EMB Wavelength Dependence
• a1 multimode fibres support longer wavelengths (SWDM)
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ISI contribution No. 3 – Chromatic dispersion Different wavelengths travel at different velocities
Laser MMF Core
Shorter wavelengths
travel slower
Pulse broadening
due to chromatic
dispersion
+i i
i
C
Bn
2
22 1
l
ll
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ISI contribution No. 4 – Modal-Chromatic dispersion Modes undergo a relative chromatic dispersion – Panduit discovery
MMF Core
l2
l1
Laser
• Combination of Modal & Chromatic disp’n
• Effect previously unknown
• Can be compensated by a1
850.452 nm 850.028 nm 849.584 nm 849.108 nml2 = l1 =
a0 fibre
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1.E-14
1.E-13
1.E-12
1.E-11
1.E-10
1.E-09
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
-13.0
-12.5
-12.0
-11.5
-11.0
-10.5
-10.0
-9.5
-9.0
-8.5
-8.0
-7.5
-7.0
Rx Power (dBm)
Impact of modal-chromatic dispersion- Same fibre manufacturer, cable, and bandwidth (4700 MHz·km)
Ch
an
ne
l b
it e
rro
r ra
te @
10
Gb
/s
PASSCompensations
MC dispersion
FAILExacerbates
MC dispersion
HigherPerformance
LowerPerformance
1
2
C26 Blue
C26 Brown
• 10 Gb/s Ethernet
• Same transceiver (850 nm)
• 300 m reach
• IEEE 802.3ae requirement, 1E-12 @ -9.9 dBm
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Multimode fibre types
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Laser Optimized Multimode Fibre TypesFibre Sorted and Classified Based on Quality of Modal Dispersion
Fibre TypeEMB at 850 nm
(MHz·km)
EMB at 953 nm
(MHz·km)
OM3 2000 NA
OM4 4700 NA
OM5 4700 2470
Signature Core OM4+ 5500 2000
• MMF is sorted as OM3 & OM4 based on Effective Modal Bandwidth (EMB)
• EMB is calculated from a Differential Mode Delay (DMD) measurement, i.e., modal dispersion
• OM3 and OM4 are designed for 850nm transmission and minimum channel reaches of 100 m and 150 m respectively
• OM5 includes a specified EMB at a longer wavelength (953nm)• Only provides a benefit for SWDM-4 applications where the required reach exceeds the standards specified
maximum channel reach (non-standard)
• Signature Core OM4+ is a dispersion compensating (a1) OM4 fibre
50% a1 & 50% a2
50% a1 & 50% a2
~ a1
Only a1
Alpha profiles
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OM5 – Wide Band Multimode Fibre
• OM5 was developed under a TIA Joint Task Group ‒ Organized under the TR42.12 and TR42.11 Subcommittees
‒ TR42-12 Vice-Chaired by Panduit, Dr. Brett Lane
‒ Task Group Chaired by Panduit
‒ EMB shifted for longer wavelength operation‒ Higher bandwidth at 953 nm
‒ Similar bandwidth at 850 nm
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TIA Round Robin ReportUsed For Specifying OM5 Chromatic Dispersion
Source: TR42.12-2015-06-022
Round Robin
Participants
1. Corning
2. OFS
3. Panduit
4. Prysmian
5. J fibre
6. YOFC
Standard MMF
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Future of Multimode FibreLowest cost for short reach applications
Switch-to-server interconnections
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Optical
Transmitter
Optical
Transmitter
Optical
Transmitter
Optical
Transmitter
PMD
Service
Interface
MDI
Optical
Receiver
Optical
Receiver
Optical
Receiver
Optical
Receiver
PMD
Service
Interface
L0
L1
L2
L3
L0
L1
L2
L3
l0
l0
l0
l0
Patch
Cord
Multimode Optical
fibre Cable
MDI
4 fibres x 50 Gb/s(parallel optics)
Supports Breakout Functionality
Block Diagram For 200 GbE Parallel Optics Transmit/Receive Paths
For clarity, only one direction of transmission is shown
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32 25
48 Servers
Patch Panel
.
.
.
ASIC
256 x 50G
…
…
…
…
1 -
86
4
65 - 72 128
12
9 -
13
61
92
193 -200256
40
0G
1 2 6 24
40
0G
40
0G
40
0G
40
0G
40
0G
48 Servers
Patch Panel
.
.
.48 Servers
Patch Panel
.
.
.48 Servers
Patch Panel
.
.
.
…
…
…
. . .
6 x 8 = 48
50G servers
. . .
Multimode Fibre Application: Server BreakoutEx: 256 x 50G Switch Radix – 3:1 Over Subscription
• ASIC – Application Specific Integrated Circuit
• High density 32 x 400G switch ports
• 50G servers supported by- 400GBASE-SR8 to 50GBASE-SR breakout
8 x 400G (64 x 50G) Uplinks (3.2 Tb)
24x 400G (192 x 50G) Downlinks (9.6 Tb)
4 racks of 48 servers
6 switch ports / Rack
6x 16f MPO to 48 duplex LCs
4 rack of 48 servers
or
8 racks of 24 servers
40
0G
40
0G
40
0G
40
0G
40
0G
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SWDM = Short Wavelength Division MultiplexingMDI – Media Dependent InterfacePMD = Physical Media Dependent
Optical
Transmitter
Optical
Transmitter
Optical
Transmitter
Optical
Transmitter
PMD
Service
Interface
MDI
SW
D M
ux
SW
D d
eM
ux
Optical
Receiver
Optical
Receiver
Optical
Receiver
Optical
Receiver
PMD
Service
Interface
L0
L1
L2
L3
L0
L1
L2
L3
l0
l1
l2
l3
l0
l1
l2
l3
Patch
CordSingle-mode fibre
MDI
4 l’s x 50G
Block Diagram For SWDM4 Transmit/Receive Path
For clarity, only one direction of transmission is shown
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• SWDM requires a filter for each l, each filter adds an insertion loss ≥1.5 dB dB
• End-to-end (TX & RX) has a reduction in signal power ≥3dB
• Has a 3 dB reduction in SNR compared to parallel optics
• SWDM/OM5 Channels will have reduced reach compared to parallel optics
• Does not support port breakout
SWDM Transmission
Cross-talk
l0
l1
l2
l3
p+
n+
i
SiO2
p+
n+
i
SiO2
p+
n+
i
n-contact
p-contactsAntireflective
coating
SiO2
l0
l1 l2 l3l0 Detector
l2 Detector l2 Detector l3 Detector
p+
n+
i
Si O
2
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Double Link Channel Cost ComparisonIEEE Panduit contribution (pimpinella_NGMMF_03_0118.pdf)
200GBASE-SR4 200G SWDM4 115 mn d4.0 1.75
7.00296.00$ 518.00$
Parallel Cabling Duplex Cabling
Fiber Type = OM4 OM5
12 12
8 2
2 2
3 3
0.53 0.82
0.08 0.11
0.51 0.77
1.00 0.25
Cable fiber count =
XCVR TYPES: Cost crossover =
Cost multipliers =
Total Xcvr cost factor =
STRUCTURED CABLING:
No. of used fibers =
No. of channel links =
No. of patch cords =
Normalized Standard Costs
Material + Labor
Cable Termination =
Per meter adder =
Adapter panel or Cassette =
Patch Cord =
0.75
1.00
1.25
1.50
1.75
2.00
0 50 100 150 200 250 300
2 X
cvrs
Plu
s St
ruct
ure
d C
ab
ling
(R
ela
tive
Co
st)
Channel Reach (m)
Channel Cost Analysis
200G SWDM4
200GBASE-SR4
0.68 W 1.0 W
0.25 X1.0 X
0.65 Y 1.0 Y
0.81 Z 1.0 Z
n = cost multiplier compared to 10GBASE-SR
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Panduit contribution to IEEE – Eye safety calculatorParameter Units Notes
l = nm Wavelength each lane
Power = dBm Poewr each lane
NA = - Numberical Aperture + tolerance
N_fiber_vert - Number of fiber rows
N_fibers_horiz - Number of lit fibers in row
Distance_y mm Fiber row separtion distance
Distance_x mm Fiber pitch within row
Source size (one) mm MMF core diameter
1 = Telescope condition 1 2 3 1 2 3 1 2 3 1 2 3 Telescope, microscope, naked eye
2 = Microscope d 0 = 7.0 3.5 7.0 7.0 3.5 7.0 7.0 3.5 7.0 7.0 3.5 7.0 mm Stop aperture
3 = Naked eye L = 2000 14 100 2000 14.0 100 2000 14 100 2000 14 100 mm Source-aperture separation
worst_comb_y 1.00 1.00 1.00 1.0 1.0 1.0 1.00 1.00 1.00 1.00 1.00 1.00
worst_comb_x 1.00 1.00 1.00 1.0 1.0 1.0 1.00 1.00 1.00 1.00 1.00 1.00
total_fibers 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Number of fibers in field of view
alpha (worst) 1.50 3.57 1.50 1.50 3.57 1.50 1.50 3.57 1.50 1.50 3.57 1.50 mrad Subtense source angle
T2 10.00 10.50 10.00 10.00 10.50 10.00 10.00 10.50 10.00 10.00 10.50 10.00 sec Emission durationd 63 = 410.83 2.88 20.54 374.05 2.62 18.70 383.83 2.69 19.19 405.91 2.84 20.30 mm Beam diam. 63%
C4 = 1.941 1.941 1.941 2.228 2.228 2.228 2.559 2.559 2.559 2.938 2.938 2.938 Correction factor 4
C6 = 1.00 2.38 1.00 1.00 2.38 1.00 1.00 2.38 1.00 1.00 2.38 1.00 Correction factor 6
C7 = 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 - Correction factor 7
h 0.000 0.773 0.110 0.000 0.833 0.131 0.000 0.817 0.125 0.000 0.781 0.112 - Fraction of power accessible
Class 1 AEL 0.757 1.797 0.757 0.869 2.063 0.869 0.998 2.369 0.998 1.146 2.720 1.146 mW
Class 1M AEL 0.757 500.000 0.757 0.869 500.000 0.869 0.998 500.000 0.998 1.146 500.000 1.146 mW
2607.67 2.33 6.90 2482.02 2.48 6.65 3000.69 2.90 8.01 3852.91 3.48 10.22 mW
500.00 500.00 6.90 500.00 500.00 6.65 500.00 500.00 8.01 500.00 500.00 10.22 mW
1.884 1.884 1.884 1.884 1.884 1.884 1.884 1.884 1.884 1.884 1.884 1.884 mW
0.0007 0.8098 0.2728 0.0008 0.7600 0.2833 0.0006 0.6494 0.2351 0.0005 0.5406 0.1844 -
0.0038 0.0038 0.2728 0.0038 0.0038 0.2833 0.0038 0.0038 0.2351 0.0038 0.0038 0.1844 -
Class 1
Class 1M
Bi-directional = 01
Co-directional = 1
1.0
Class 1, 1M Emission Limits for range Wavelength 1 Wavelength 2
700 nm to 1399 nm 844 874
2.75 2.75
Wavelength 3 Wavelength 4
Hazard per wavelength per conditions Class 1M =
Condition
Class 1 Hazard 2.760 EXCEEDED
Class 1M Hazard 0.976 PASS
AEL per Class/condition
Max permissible power for hazerd 1:
Total Power per wavelength per condition:
Hazard per wavelength per conditions Class 1 =
Max permisible power for hazerd 1M:
Maximum Level
per wavelength
0.810 0.760
0.273 0.283
0.649 0.541
0.235 0.184Worst case for each wavelength
0.05
904
2.75
0.161
934
2.75
0.1700.172 0.157
1.0
0.25
0.25
1.0 = Hazard
Based on
measured
VCSELs
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Progression of Multimode Fibre Ethernet PMDs
Data Rate
Gb/sNomenclature
Lane Rate
Gb/s
Number
of
fibre pairs
Number of
wavelengths
Year
Standardized
10
40
10GBASE-SR
40GBASE-SR410
1
41
2002
2015
25
100
25GBASE-SR
100GBASE-SR425
1
41
2016
2015
50
100
200
50GBASE-SR
100GBASE-SR2
200GBASE-SR450
1
2
4
8
12018
400400GBASE-SR8
~2021400GBASE-SR4.2 4 2 BiDi
100
200
400
800
100GBASE-SR
200GBASE-SR2
400GBASE-SR4
800GBASE-SR8
100
1
2
4
8
1 TBD100G PMD
Series
50G PMD
Series
10G PMD
Series
25G PMD
Series
NEW
FUTURE?
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Multimode fibre structured cabling channel Lengths
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.0%
2.0%
4.0%
6.0%
8.0%
10.0%
12.0%
14.0%
16.0%
18.0%
20.0%
Cum
ula
tive %
% o
f channel le
ngth
s (
m)
Channel Length (m)
90% of channels less than 100 m
96.5% of channels less than 150 m
Source: Ethernet Alliance 23 March 2016
96.5%
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Single-mode FibreRequired for Long or Extended reach Applications
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Single-mode fiber types specified by ITU-T
OS2
CCITT – International Telegraph and Telephone Consultative Committee ITU – International Telegraph Union (1864), Now known as International Telecommunications Union
1988
2006/2009
NewSPS
2012
1984CCITT
Blue Book
2000
RecentlyApproved
SPS-433For
G.652.D
2003
ITU-T
SpecIEC Description OFS Corning Prysmian
1 G.652.A “Standard” SMF w/ ZDW ~1310nm. AllWave SMF-28
“Standard” SMF w/ ZDW ~1310nm,
1625nm Atten, low PMD.
“Standard” SMF w/ ZDW ~1310nm,
LWP, low PMD.5 G.653.A Dispersion –Shifted SMF. Not branded.Offered upon request.6 G.653.B Dispersion –Shifted SMF, Low PMD. Not branded. Offered upon request.7 G.654.A - Cutoff-Shifted SMF. Obsolete8 G.654.B B1.2_b Cutoff-Shifted SMF, med MFD, low PMD. TeraWave 9 G.654.C B1.2_c Cutoff-Shifted SMF, low PMD. TeraWave 10 G.654.D - Cutoff-Shifted SMF, high MFD, low PMD. TeraWave Ocean SLA+ / ULA Vascade LongLine
Non-Zero Dispersion Shifted SMF, low TrueWave RS,
1625nm bend. TrueWave LA (Large Area)
Non-Zero Dispersion Shifted SMF, positive TeraLight,
dispersion, low 1625nm bend. TeraLight Ultra
14 G.656 B5 Non-Zero Dispersion Shifted SMF for Wideband. TrueWave REACHTeraLight,
TeraLight Ultra
16 G.657.A2 B6_aBending-Loss Insensitive SMF, r =7.5mm,
G.652.D compliant. AllWave FLEX+ClearCurve LBL BendBright-XS
17 G.657.B2 B6_b Bending-Loss Insensitive SMF, r =7.5mm AllWave FLEX Max ClearCurve LBL BendBright-XS
AllWave FLEX Max, EZ-Bend (r=2.5mm)
B1.12 G.652.B AllWave SSMF
3 G.652 C B1.3 AllWave“Standard” SMF w/ ZDW ~1310nm, LWP
4 G.652 D B1.3 AllWave, AllWave FLEXSMF-28e
SMF-28e+ESMF
B2
11 G.655.C B4_c Non-Zero Dispersion Shifted SMF Leaf
12 G.655.D B4_d Leaf
TrueWave RS, TrueWave REACH,
TrueWave LA (Large Area)
13 G.655.E B4_e TrueWave REACH
15 G.657.A1 B6_aBending-Loss Insensitive SMF, r =10mm, G.652.D
compliant.ClearCurve XB Bendbright
18 G.657.B3 B6_b Bending-Loss Insensitive SMF, r =5mm ClearCurve ZBL BrendBright Elite
AllWave+
OS1Obsolete
Transitioning
away from
G.652.D (OS2)
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© 2018 Panduit Corp. All Rights Reserved.
Hyperscale data center Ethernet Market
50/100/200/400GE
Approaches 50% of All
Data Center Ports by 2021
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IEEE 802.3 MMF Ethernet Data Rate Timeline
2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028
10/40GbE Ecosystem802.3ba
802.3bj
802.3bm
802.3by
25/100GbE Ecosystem
42.11 SWDM Ecosystem 50-200GTIA Wide-band MMF (OM5)
Single-lane 25G
Twin-ax
4x25G
n x 100G PAM-4 Ecosystem
n x 50G PAM-4 Ecosystem 50-400G802.3cd
n x 64G PAM-4 EcosystemFC PI-7
802.3 CFI
We are here
YEAR
• MMF will support future higher-speed Ethernet
• Maximum data rate determines maximum reach
• SMF required for reach > 150 m
• Parallel optics is best choice for future proofing
Summary:
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The future of optical fibre in the data centerDr. Rick Pimpinella, Panduit Fellow
THANK YOU