1. Best Practices for Ensuring Fiber Optic System Performance
Inspection, Cleaning, Testing

2. Agenda Fiber Optics Key Concepts Inspection and Cleaning Testing
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
Wide variety of people on the phone – need to make sure everyone is on the same page.

3. Optical Communications
Communication technology, developed in the 70s, that sends optical signals down hair-thin strands of glass fiber
Transmitter
Receiver
Light Rays
Fiber
Fiber optics is a communication technology developed in the 1970s and became widely deployed by the 1990s. It is now the primary transport medium in all types of telecommunications networks. Very simply, fiber optic communication transmits optical signals down very thin glass fiber strands to a receiver.

4. Optical Fiber Types 2 Types Multimode Single-mode
Two basic types of fiber optic cables are used: Multimode and Single-mode. Details of how light travels down these two types of fiber will be addressed on the following two slides. Physically, both fiber types are made up of a glass core surrounded by a glass cladding. A protective buffer then covers the fiber that is typically stripped off when terminating a fiber.
The core of a multimode fiber is either 50 or 62.5 microns wide.
The core of a single-mode fiber is typically 9 microns wide.
Both multimode and single-mode fiber cores are surrounded by a 125 micron cladding.
The buffer takes the total diameter of the fiber to either 250 or 900 microns.
Note that these examples show simplex fiber cables. Multi-strand fiber cables also exist.

5. Fiber Types MM
Fiber carries numerous light rays (mode) simultaneously through the fiber.
Light traveling through multimode fiber takes multiple paths or modes, which causes the light pulses to spread out or disperse. The result of this pulse spreading is that multimode fiber cannot carry high bit rates over long distances. Multimode fiber is typically found in local area networks working at 850 or 1300 nanometers. While the fiber optic cable itself is not significantly cheaper than single-mode fiber, the light sources are. Multimode fiber uses LEDs or VCSEL (cheap lasers) as light sources compared to lasers for single-mode fiber.
Refractive index: Measures the speed of light in a material. For example, n1 and n2 are the respective refractive index of the cladding and the core, and n1<n2 is the condition for the light traveling down the fiber.
Fiber channel and Ethernet are most common applications
High attenuation
850 to 1300 nm transmission wavelengths
Local networks (<2 km)
Limited bandwidth
LAN/Industry

6. Fiber carries a single light ray (mode).
Fiber Types SM
Fiber carries a single light ray (mode).
Low attenuation
1260 to 1660 nm transmission wavelengths
Access/medium/long haul networks (>200 km)
Nearly infinite bandwidth
Telecom/CATV
FTTx
CWDM/DWDM
Outside plant fiber optic cable uses single-mode fiber. Working at 1310, 1550, and other wavelengths in the 1260 to 1660 nanometer range, single-mode fiber can carry very high bit rates over long distances. Because the core of the fiber is so small, light can only take a single path through it, minimizing the amount of dispersion.
Single-mode fiber is also used in wavelength division multiplexing systems, which have multiple wavelengths of light traveling on the same fiber.
Ethernet/FICON on SM is popular in enterprise

7. 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.
Local Convergence Point
Buildings
Network Access Points
CO/Headend/MTSO
Use the phrase: Moves, adds, changes
Close slide with “connectors are everywhere”
Feeder Cables
Distribution Cables
Multi-home Units
Residential
Drop Cables

8. Fiber Optic Connector SC Connector
BODY
FERRULE
SC Connector
CLADDING
FIBER
CORE
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.
The fiber connector uses a latch and key mechanism to align the fiber and prevents the rotation of ferrules of the two mated connectors.

9. Anatomy of Fiber Connectors
Light is transmitted and retained in the CORE of the optical fiber by total internal reflection.
Single-mode Fiber Structure
Single-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.
Fiber End Face View
FERRULE – 1.25 or 2.5 mm
CLADDING – 125 µ
CORE – 9 µ

10. 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®

11. Connector Types FC connector SC Connector ST Connector 2.5 mm ferrule
Screw mechanism with key –aligned
Mainly used with single-mode fibers
SC Connector
2.5 mm ferrule
Push-pull latching mechanism
Most widely used connector today (LAN/WAN)
ST Connector
2.5 mm ferrule
Twist-lock mechanism
Mainly used with multimode fibers
This slide shows the most common connectors found in North America today.
Finger connector
Stick and click
Stick and twist
Many of these connectors are available as PC or APC.
SC Connector is the connector used in the LAN

12. Connector Types MU Connector LC Connector E2000 Connector
1.25 mm ferrule
Push-pull latching mechanism
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
MU – looks like a cow
LC – Little Connector
DIN Connector
2.5 mm ferrule
Anti-rotation keyed
Used mainly in EU

13. The angle reduces the back-reflection of the connection.
Types of End Faces
PC – Physical Contact
APC – Angled Physical Contact
The angle reduces the back-reflection of the connection.
APC connectors are used in systems where back reflection is an issue such HIGH-POWER applications. Video is typically high-power, so APC connectors are found in CATV and FTTx environments.
SC - PC
SC - APC

14. Focus on the Connection
Bulkhead Adapter
Ferrule
Fiber
Fiber Connector
Alignment Sleeve
Alignment Sleeve
Physical Contact
Note there are two endfaces – one in the bulkhead and one on the patch cord.

15. What Makes a GOOD Fiber Connection?
The 3 basic principles that are critical to achieving an efficient fiber optic connection are “The 3 Ps”:
Light Transmitted
Perfect Core Alignment
Physical Contact
Pristine Connector Interface
Core
Cladding
CLEAN
Today’s connector design and production techniques have eliminated most of the challenges to achieving core alignment and physical contact.

16. What Makes a BAD Fiber Connection?
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.
A single particle mated into the core of a fiber can cause significant back reflection, insertion loss, and even equipment damage.
Light
Back Reflection
Insertion Loss
Core
Cladding
Emphasis on Contamination being the No. 1 reason for troubleshooting
DIRT

17. Measurement Units dBm unit is decibels relative to 1 mW of power
dBm is an ABSOLUTE measurement
dB is a RELATIVE measurement
1 mW = 0 dBm Tx
Relative Power (dB) =10*Log
2 dB
1 dB
Loss = 8 dB
Absolute Power (dBm) =10*Log
5 dB
When we move into the section that discusses testing, the difference between dB and dBm will become critical. Simply put, dBm is an ABSOLUTE measurement: 1 mW equals 0 dBm, while dB is a relative measurement.
The diagram on the right side of the slide illustrates this. At the top a transmitter is generating 0dBm – an absolute value. At the bottom a receiver is receiving -8 dBm, again an absolute value. Between the transmitter and the receiver are two fiber optic cables and a single fiber connector that, combined, create a loss of 8 dB—a relative value. In other words, loss is never referred to in dBm because it is always a relative value. We could change the transmitted level to +8 dBm and the received level would then become 0 dBm, because the relative amount of loss is still 8 dB.
Make note of loss shown at connection – want connector to be about .75dB of loss – most volatile point
-8 dBm Rx
0 dBm
-3 dBm
-20 dBm
-40 dBm
1 mW
0.5 mW
0.01 mW mW

18. Optical Loss Budget
Transmitter
Receiver
Light Rays
Fiber
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.
When installing a fiber network, network topology and equipment specifications must be considered. One of the major parameters requiring
measurement is optical loss budget, or end-to-end optical link loss. When calculating the optical loss budget of a fiber link, the source,
detector, and optical transmission line must be considered. Optical loss budget must account for both link loss and system power margins.
These power margins cover allowances for the effects of environment, aging, and eventual repairs.

19. Contamination and Signal Performance
Fiber Contamination and Its Effect on Signal Performance 1
CLEAN CONNECTION
Back Reflection = dB
Total Loss = dB 3
DIRTY CONNECTION
Make connection to link budget.
Make the point that where the contamination is makes a difference
Clean Connection vs. Dirty Connection
OTDR trace illustration of the significant decrease in signal performance after mating dirty connectors
Back Reflection = dB
Total Loss = 4.87 dB

20. Illustration of Particle Migration
11.8µ
15.1µ
10.3µ
Core
Cladding
Actual fiber end face images of particle migration
Emphasis on what happens over time with a little bit of contamination never being caught.
Even though the contamination at the beginning was not in the core, it can easily migrate to the core.
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.

21. Particle Migration and Signal Performance
-70
-60
-50
-40
-30
-20
Baseline/ Initial Contamination
1st Mating
2nd Mating
3rd Mating
Actual fiber end face images of particle migration
Importance is where the contamination is.
For each successive mating, actual dB values increase as signal performance decreases
Dirt particles near or on the fiber core significantly affect signal performance

22. Types of Contamination
Fiber end faces must be free of any contamination or defects, as shown below:
Single Mode Fiber
Common types of contamination and defects include the following:
Dirt
Oil
Pits & Chips
Scratches

23. Contamination Categories
LOOSE
Most contamination comes from dry particles that have fallen onto the end face or have been “placed” there during handling
BONDED
Most stubborn particles are held in place with grease, oils, or dried residue from a wet cleaning process
MATED
Particles 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

24. Inspection and Cleaning

25. Inspect Before You Connectsm
Follow the simple “INSPECT BEFORE YOU CONNECT” process to ensure fiber end faces are clean prior to mating connectors.

26. Inspect, Clean, Inspect, and Go!
Fiber inspection and cleaning are SIMPLE steps with immense benefits. 1
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. 2
Clean
■ If the fiber is dirty, use a simple cleaning tool to CLEAN the fiber surface. 3
Re-inspect 4
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.
■ 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.

27. 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.
Inspection is contact-free. Discuss or have separate slide.
Patch Cord (Male) Inspection
Bulkhead (Female) Inspection
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.

28. 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 Mating
Fiber AFTER Cleaning
Dirty Fiber PRIOR to Mating
Fiber AFTER Mating and Numerous Cleanings
Common mistake is to reactively inspect fiber endfaces

29. Benefits of Proactive Inspection
PROACTIVE INSPECTION is quick and easy, with indisputable benefits
Reduce Network Downtime
Active network = satisfied customers
Reduce Troubleshooting
Prevent costly truck rolls and service calls
Optimize Signal Performance
Network components operate at highest level of performance
Prevent Network Damage
Ensure longevity of costly network equipment

30. 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!
Whatever cleaning equipment you use, make sure it is designed for fiber optic cleaning.

31. Testing

32. Test! Basic Tests Advanced 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)

33. 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).

34. Insertion Loss
Single Direction Insertion Loss Measurement with a Source and Power Meter
Reference first!
Light Source
Power Meter
0dB
Reference Measurement
Light Source
Power Meter
-1.5dB
Jumper or patch-cord
Bi-Directional LS and PM
PocketClass
Smart Optical -
Insertion Loss Measurement
1, 2, or 3 jumper references can be performed – 2 jumper shown

35. 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
1490 / 1550 nm
OLP-57/02
1490 / 1550 nm
ONT
OLT
1310 nm
1310 nm
Meter 3
Meter 1
Meter 2 2
OLP-57: Provides 3 power
meters in one
1310 nm
1490 nm
1550 nm

36. 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

37. Wrap-up

38. Always “INSPECT BEFORE YOU CONNECT”
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

39. 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

40. Questions and Resources?
Questions & Answers
for:
Posters,
White Papers,
Reference Guide to Fiber Optic Testing
Product and Service Information
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