best practices for ensuring fiber optic system performance inspection, cleaning, testing
TRANSCRIPT
Best Practices for Ensuring Fiber Optic System Performance
Inspection, Cleaning, Testing
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Agenda
Fiber Optics Key Concepts– Fiber types and Connectors– Fiber Connections: the good, the bad, and the ugly– Measurement Units
Inspection and Cleaning– Inspect Before You ConnectSM
– Inspect Both Sides– Proactive Inspection– Cleaning Best Practices
Testing– Basic– Advanced
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Optical Communications
Communication technology, developed in the 70s, that sends optical signals down hair-thin strands of glass fiber
Transmitter Receiver
Light Rays Fiber
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Optical Fiber Types
Multimode Single-mode
2 Types
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Fiber Types MM
– High attenuation– 850 to 1300 nm transmission wavelengths– Local networks (<2 km)– Limited bandwidth– LAN/Industry
Fiber carries numerous light rays (mode) simultaneously through the fiber.
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Fiber Types SM
– Low attenuation– 1260 to 1660 nm transmission wavelengths– Access/medium/long haul networks (>200 km)– Nearly infinite bandwidth– Telecom/CATV– FTTx – CWDM/DWDM
Fiber carries a single light ray (mode).
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Fiber Connectors are Everywhere!
Fiber optic connectors are common throughout the network as they
provide the power to add, drop, move, and change the network.
Buildings
Multi-home UnitsResidential
CO/
Headend/
MTSO
Local Convergence Point
Network Access Points
Feeder Cables
Distribution Cables
Drop Cables
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Fiber Optic Connector
SC Connector
The BODY houses the ferrule to secure the fiber in place.
The FERRULE is a small cylinder used to mount the fiber and acts as the alignment mechanism. The end of the fiber is located at the end of the ferrule.
The FIBER comprises 2 layers: the CLADDING and the CORE.
– The CLADDING is a glass layer surrounding the core, which prevents the signal in the core from escaping.
– The CORE is the critical center layer of the fiber and the conduit that light passes through.
Fiber connectors have extremely tight tolerances with the potential to make a low-loss connection. To achieve this potential, they must be handled and mated properly.
BODYBODY
FERRULEFERRULE
FIBERFIBER
CLADDINGCLADDING
CORECORE
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Anatomy of Fiber Connectors
Light is transmitted and retained in the CORE of the optical fiber by total internal reflection.
Single-mode Fiber StructureSingle-mode fibers carry a single ray of light, making them better in retaining the fidelity of light over long distances.
The fiber connector endface has 3 major areas – the core, the cladding and the ferrule. Particles closer to the core will have more impact than those farther out.
CORE – 9 µCORE – 9 µ
CLADDING – 125 µCLADDING – 125 µ
FERRULE – 1.25 or 2.5 mm
FERRULE – 1.25 or 2.5 mm
Fiber End Face View
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Single Fiber vs. Multi-Fiber Connectors
SINGLE FIBER CONNECTOR MULTI-FIBER CONNECTOR
White ceramic ferrule One fiber per connector Common types include SC,
LC, FC, and ST
Polymer ferrule Multiple fibers in linear array
(for example, 8, 12, 24, 48, and 72) in single connector providing high-density connectivity
Common type is MPO or MTP®
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Connector Types
SC Connector– 2.5 mm ferrule
– Push-pull latching mechanism
– Most widely used connector today (LAN/WAN)
FC connector– 2.5 mm ferrule
– Screw mechanism with key –aligned
– Mainly used with single-mode fibers
ST Connector– 2.5 mm ferrule
– Twist-lock mechanism
– Mainly used with multimode fibers
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Connector Types
LC Connector– 1.25 mm ferrule
– Finger latch
– Fastest growing connector
E2000 Connector– 2.5 mm ferrule
– Finger latch with a protective cap over the ferrule
DIN Connector– 2.5 mm ferrule
– Anti-rotation keyed
– Used mainly in EU
MU Connector– 1.25 mm ferrule
– Push-pull latching mechanism
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Types of End Faces
PC – Physical Contact APC – Angled Physical Contact
The angle reduces the back-reflection of the connection.
SC - PC SC - APC
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Focus on the Connection
Bulkhead Adapter
Fiber Connector
Alignment Sleeve
Alignment Sleeve
Physical Contact
FiberFerrule
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What Makes a GOOD Fiber Connection?
Perfect Core Alignment
Physical Contact
Pristine Connector Interface
The 3 basic principles that are critical to achieving an efficient fiber
optic connection are “The 3 Ps”:
Core
Cladding
CLEAN
Light Transmitted
Today’s connector design and production techniques have eliminated most of the challenges to achieving core alignment and physical contact.
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What Makes a BAD Fiber Connection?
A single particle mated into the core of a fiber can cause significant back reflection, insertion loss, and even equipment damage.
Today’s connector design and production techniques have eliminated
most of the challenges to achieving core alignment and physical contact.
The remaining challenge is maintaining a pristine end face. As a result,
CONTAMINATION is the No. 1 reason for troubleshooting in optical
networks.
DIRT
Core
Cladding
Back Reflection Insertion LossLight
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Measurement Units
dBm unit is decibels relative to 1 mW of power dBm is an ABSOLUTE measurement dB is a RELATIVE measurement
Relative Power (dB) =10*Log)(
)(
mWPt
mWPi
0 dBm -3 dBm -20 dBm -40 dBm
1 mW 0.5 mW 0.01 mW 0.0001 mW
Tx
Rx
2 dB
5 dB
1 mW = 0 dBm
1 dBLoss = 8 dB
-8 dBm
Absolute Power (dBm) =10*LogmW
mWPi
1
)(
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Optical Loss Budget
What is the average output power of the transmitter? What is the minimum sensitivity of the receiver? The difference is the maximum amount of LOSS allowable
for the optical transmission line.
Transmitter Receiver
Light Rays Fiber
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Contamination and Signal Performance
Fiber Contamination and Its Effect on Signal PerformanceCLEAN CONNECTION
Back Reflection = -67.5 dBTotal Loss = 0.250 dB
11
DIRTY CONNECTION
Back Reflection = -32.5 dBTotal Loss = 4.87 dB
33
Clean Connection vs. Dirty Connection
OTDR trace illustration of the significant decrease in signal performance after mating dirty connectors
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Illustration of Particle Migration
Each time connectors are mated, particles around the core become displaced, causing them to migrate and spread across the fiber surface.
Particles larger than 5 µ usually explode and multiply upon mating.
Large particles can create barriers (air gaps) that prevent physical contact.
Particles smaller than 5 µ tend to embed into the fiber surface creating pits and chips.
11.8µ
15.1µ
10.3µ
Actual fiber end face images of particle migration
Core
Cladding
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Particle Migration and Signal Performance
For each successive mating, actual dB values increase as signal performance decreases
Dirt particles near or on the fiber core significantly affect signal performance
Actual fiber end face images of particle migration
-20
-30
-40
-50
-60
-70
Baseline/Initial
Contamination
1st Mating 2nd Mating 3rd Mating
Signal Performance
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Types of Contamination
Fiber end faces must be free of any contamination or defects, as shown below:
Common types of contamination and defects include the following:
Dirt Oil Pits & Chips Scratches
Single Mode Fiber
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Contamination Categories
LOOSEMost contamination comes from dry particles that have fallen onto the end face or have been “placed” there during handling
BONDEDMost stubborn particles are held in place with grease, oils, or dried residue from a wet cleaning process
MATEDParticles on the end face of a connector can also become embedded into the glass if mated with another connector
CONTAMINATION MUST BE CLEANED from the end face prior to mating in order to optimize the efficiency of an optical signal or interconnect
Inspection and Cleaning
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Inspect Before You Connectsm
Follow the simple “INSPECT BEFORE YOU CONNECT” process to ensure
fiber end faces are clean prior to mating connectors.
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Inspect, Clean, Inspect, and Go!
Fiber inspection and cleaning are SIMPLE steps with immense benefits.
44 Connect
■ If the fiber is clean, CONNECT the connector.
NOTE: Be sure to inspect both sides (patch cord “male” and bulkhead “female”) of the fiber interconnect.
22 Clean
■ If the fiber is dirty, use a simple cleaning tool to CLEAN the fiber surface.
11 Inspect
■ Use a probe microscope to INSPECT the fiber.
– If the fiber is dirty, go to Step 2, Clean.
– If the fiber is clean, go to Step 4, Connect.
33 Re-inspect
■ Use a probe microscope to RE-INSPECT (confirm fiber is clean).
– If the fiber is still dirty, repeat Step 2, Clean.
– If the fiber is clean, go to Step 4, Connect.
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Inspect and Clean Both Connectors in Pairs!
Inspecting BOTH sides of the connection is the ONLY WAY to ensure
the connector will be free of contamination and defects.
Patch cords are easy to access and view compared to the fiber inside the bulkhead (or test equipment or network equipment) which are frequently overlooked. The bulkhead side may only be half of the connection, but it is far more likely to be dirty and problematic.
Bulkhead (Female) InspectionPatch Cord (Male) Inspection
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Proactive vs. Reactive Inspection
PROACTIVE INSPECTION:
Visually inspect fiber connectors at every stage of handling BEFORE mating them.
Connectors are much easier to clean prior to mating, before embedding debris into the fiber.
REACTIVE INSPECTION:
Visually inspect fiber connectors AFTER discovering a problem, typically during troubleshooting.
By this time, connectors and other equipment may have suffered permanent damage.
Dirty Fiber PRIOR to MatingFiber AFTER Mating and
Numerous Cleanings
Dirty Fiber PRIOR to
Mating
Fiber AFTER Cleaning
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Benefits of Proactive Inspection
Reduce Network Downtime Active network = satisfied customers
Reduce Troubleshooting Prevent costly truck rolls and service calls
Optimize Signal PerformanceNetwork components operate at
highest level of performance
Prevent Network Damage Ensure longevity of costly network equipment
PROACTIVE INSPECTION is quick and
easy, with indisputable benefits
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Cleaning Best Practices
Many tools exist to clean fiber Many companies have their own “best practices” Dry clean first. If that does not clean, then try wet
cleaning. Always finish with dry cleaning!
Testing
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Test!
Basic Tests– Visual Fault Locator (VFL)– Optical Insertion Loss– Optical Power Levels
Advanced Tests– Optical Return Loss (ORL)– Optical Time Domain Reflectometer (OTDR)– Chromatic Dispersion (CD)– Polarization Mode Dispersion (PMD)– Optical Spectral Analysis (OSA)
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Visual Fault Locator
VFLs provide a visible red light source useful for identifying fiber locations, detecting faults due to bending or poor connectorization, and to confirming continuity.
VFL sources can be modulated in a number of formats to help identify the correct VFL (where a number of VFL tests may be performed).
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Insertion Loss
Single Direction Insertion Loss Measurement with a Source and Power Meter
Light Source
Power Meter
Reference Measurement
Light Source
Power Meter
Insertion Loss Measurement
0dB
-1.5dB
Reference first!
1, 2, or 3 jumper references can be performed – 2 jumper shown
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Measuring Power Levels - PON/FTTx
OLP-57 wavelength selective Power Meter– Handles downstream at 1490 and 1550 nm– Handles upstream at 1310 nm– Through-mode capability (1 input + 1 output)– Burst-mode capability
1310 nm 1490 nm
1490 / 1550 nm
1310 nm
2
ONT1310 nm
Meter1
Meter2
1550 nm
Meter3
OLP-57/02 1490 / 1550 nm
OLT
OLP-57:Provides 3 power meters in one
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Advanced Tests
Optical Return Loss (ORL) Optical Time Domain Reflectometer (OTDR)
– Detect, locate, and measure events at any location on the fiber link
Fiber Characterization– Determines the services that the fiber can be carry– Basic tests plus:
• Chromatic Dispersion (CD)
• Polarization Mode Dispersion (PMD)
Optical Spectrum Analysis (OSA)– Spectral analysis for Wavelength Division Multiplexing (WDM)
systems
Wrap-up
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Summary
Always “INSPECT BEFORE YOU CONNECT” Correct testing of the fiber optic link is critical
– Tests range from basic VFL/OIL to advanced OTDR/PMD/CD
– Tests to perform depend on the network (For example, LAN, CATV, FTTx, Access, Metro, or Long Haul)
JDSU CommTest provides the tools and services to ensure the performance of your fiber optic system!
We are the World Leader in fiber video inspection
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Fiber Inspection and Test Kits
Many different kits are available:– Inspection only– Inspection and cleaning– Inspection, cleaning, and testing
Example:– FIT-S001 (LAN/WAN) includes:
• OLS-5, OLS-6, OLP-5
• 200X Probe hardwired to HD3 display
• Various tips (ST, SC, SC-APC, LC, U25, and U12)
• Cleaning materials
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Questions and Resources?
Questions & Answers www.JDSU.com/inspect for:
– Posters, – White Papers, – Reference Guide to Fiber Optic Testing– Product and Service Information
Recorded Webinar is posted to www.JDSU.com/test-webcasts
Contact Us:– [email protected]