Fiber Optic Cable Assemblies Fiber Basics and...
Transcript of Fiber Optic Cable Assemblies Fiber Basics and...
Proprietary and Confidential © 2014 Amphenol
Fiber Optic Cable Assemblies
Fiber Basics
and Theory
Proprietary and Confidential © 2014 Amphenol
Fiber Optic Basics & Terminology
What is a fiber?• A fiber is an optical
waveguide ; a medium for
transferring information in
the form of light across
glass
A fiber is to light what
a hose is to water!!!
Proprietary and Confidential © 2013 Amphenol
Fiber Optic Benefits:
• Low attenuation (significant savings
on repeaters)
• Small size and weight
• Large bandwidth
• Longer lengths (in excess of 20km)
• Easy to install/maintain
• Enhanced security
• Non-conductive
• All-dielectric designs available
• No EMI/cross talk concerns
•Designed for future high-bandwidth
applications
Optical Parameters - Benefits
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Optical Parameters - History
• 1880: Alexander Graham Bell invented the Photophone
• 1954: Abraham van Heel demonstrated core-clad technology
• 1958: LASER invented
• 1970: Corning developed the first low loss fiber (<20 dB/km)
• Late 1970s: The first commercial fiber optic systems were deployed
• 1984: First single mode system
• 1987: First dispersion shifted fiber
• 1998: First non-zero dispersion shifted fiber (LEAF fiber)
• 2000: Emergence of Gigabit Ethernet Multimode Fiber
• 2005: Reduced bend radius fiber solutions
• 2010: High bandwidth multimode fiber solutions
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Optical Parameters -Transmission Sequence
•Information is encoded as electrical signal and converted to optical signal.
•Can be analog or digital.
•Light is transmitted down the fiber.
•Detector receives signal and decoder converts the signal to electrical.
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2014 Amphenol
Fiber OpticBasics & Terminology
Types of Fiber
Optical Single-mode (OS2)
Core/cladding diameter: 9/125um
Single path/mode through fiber eliminates distortion from overlapping light pulses
Can go a longer distance than multi-mode fiber, but requires a light source with a narrow spectral width, which makes the equipment quite costly
Optical Multi-mode (OM1, OM2, OM3, OM4)
• Core/cladding diameter: 62.5/125um, 50/125um
• Light waves dispersed through numerous paths/modes through fiber
• Able to carry more data than single-mode fiber, but is best for shorter distances because of higher attenuation values and optical dispersion
Proprietary and Confidential © 2014 Amphenol
Fiber OpticBasics & Terminology
Physical Characteristics of Fiber
Cladding Core
Multimode 140m 100m
Step Index
125m 50m
Multimode 125m 62.5m
Graded Index 140m 100m
Single Mode 125m 8.5m
Step Index 125m 9m
Dispersion
High-Order Mode
Low-Order Mode
Proprietary and Confidential © 2014 Amphenol
Fiber Type
Core Cladding (µm) Standard
Jacket Color
minEMB (MHz·km) 1G 10G 40G 100G Cost
OM1 62.5/125TIA-492AAAA
IEC 60793-2-10 Orange 200 275 33 $
OM2 50/125TIA-492AAAB
IEC 60793-2-10 Orange 500 550 82 $
OM3Laser optimized
50/125TIA-492AAAC
IEC 60793-2-10 Aqua 2000 800 300 100 100 $$$
OM4Laser optimized
50/125TIA-492AAAD
IEC 60793-2-10Currently
Aqua 4700 1000 550 125 125 $$$$
• ~85% of data center links are 100m or less
Typical Max Reach (m) for 850nm Ethernet
Key factors for choosing a fiber type Current and future data rates, bandwidth needs, reach, cost
Fiber OpticOptical Multi-mode (OM) Fiber
Proprietary and Confidential © 2014 Amphenol
OM3 and OM4 fiber types are recommended for data centers
Optimized for laser-based 850nm operation with a much higher minimum effective modal bandwidth (EMB) and longer distance capability
Dominant in data centers due to emergence of high data rate stems, such as 10, 40, 100Gigabit Ethernet and 8 and 16 Gigabit Fibre Channel
Cable, connectors, hardware, and electronics are now readily available to support usage of this fiber
Industry has recognized the benefits of this fiber
IEEE 40/100G
Fibre Channel 4/8/16G transmission standards
TIA-568-G3 structured cabling and connectivity standards
Most economical solution due to electronic costs
Data rate scalability ensures support for both legacy and future application needs
Fiber OpticOptical Multi-mode (OM) Fiber
Proprietary and Confidential © 2014 Amphenol
Multi-mode (M/M) • RL ≤ -45dB
• Usually hole diameter of ≥127um depending on the connector
• Connector color code is typically: Beige or Black
• SMA hole diameter goes to 1500um
Single mode (S/M) • UPC ultra polish
• RL ≤ -55dB
• Usually 125um, 125.5um, or 126um
• Color code typically: Blue
Single mode Angled• APC angled polish
• RL ≤ -65dB
• Color code typically: Green
UPC
Fiber OpticBasics & Terminology
Typical Polish Types
Keeping the endface
clean is critical
Proprietary and Confidential © 2014 Amphenol
Fiber OpticCable Types
Examples of Loose Tube Buffer and Tight Buffer Constructions
Loose Tube Buffer
Coated Optical Fiber
Tight Buffer
Buffer Layers Applied Directly
Over Fiber Coating
Proprietary and Confidential © 2014 Amphenol
Zipcord Distribution Loose Tube Breakout
Simplex- Available in 900µm, 1.6mm, 2mm, 2.9mm
Zipcord- Available in 1.6mm, 2mm, 2.9mm
Ribbon Cable- Available in fiber counts of 4, 8, 12, 24
Distribution- Tight buffered 900µm. Available in a variety of fiber counts.
Breakout-Tight buffered fibers enclosed in subunits throughout the cable.
Available in a variety of fiber counts. Subunit sizes range from 1.6mm to
2.9mm.
Outside plant (OSP)- 250µm loose tube construction. Available in a
variety of fiber counts, armored or non-armored.
Fiber OpticCable Types
Proprietary and Confidential © 2014 Amphenol
Fiber OpticBasics & Terminology
Attenuation
• Measure the decrease in transmitted optical power and is expressed in decibels per kilometer (dB/Km)
Casual Factors:
– Absorption
– Impurities
– Scattering
– Variances in the structure of the fiber
– Micro/Macro Bending
Insertion loss
• The attenuation caused by the insertion of an optical component (i.e. a connector or coupler in an optical transmission system)
Return loss
• Ratio of incidental optical power to the reflected optical power.
The scattering of light in the direction opposite to its original
propagation
Proprietary and Confidential © 2014 Amphenol
Attenuation is the loss of optical power, measured in
decibels (dB).
ATTENUATION (dB) = -10 log (Powerout/Powerin )
Power is measured in watts (mW or µW).
The negative sign gives attenuation a positive value,
since input power is always greater than output power
for passive optical devices.
14
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Optical Parameters - Attenuation
Absorption: light is absorbed by impurities in the
glass
• Accounts for about 5% of intrinsic attenuation
• Light is absorbed by impurities introduced during
the manufacturing process
Absorption
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Optical Parameters - Attenuation
Scattering: Technically referred to as Rayleigh
scattering, it accounts for about 95% of intrinsic
attenuation
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Macro-bendingOptical fiber bends that are much larger and visible.
Typically caused by bending the cable beyond the
specified bend radius. Attenuation is increased by
light escaping through these bends.
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Micro-bendingSharp microscopic curvatures in optical fiber on the
order of a few micrometers.Typically caused by shrinking of the buffer or poor
cable manufacturing methods.
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Index of refraction: (‘IOR’ or ‘n’) is a way of
measuring the speed of light in a material:
IOR: Speed of light in a vacuum
Speed of light in the material
Medium IOR or n Speed
Vacuum 1.0000 Faster
Air 1.0003
Water 1.33
Cladding 1.46
Core 1.48 Slower
Optical Parameters - Index of Refraction
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Optical Parameters - Refraction and Total Internal Reflection
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Optical Parameters - The Critical Angle
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
455 nm Violet
650 nm Green
750 nm Red
850 nm Short Wavelength lasers/LEDs
1310 nm Long Wavelength Lasers/LEDs
1550 nm Long Wavelength Lasers
Fiber
Optic
Applications
Visible
Spectrum
Higher Frequency
Optical Parameters - The Optical Spectrum
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Optical Parameters - Operating windows
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Optical Parameters - Numerical Aperture
In practical terms, the numerical aperture describes the ability of a
fiber to collect light. A larger NA fiber has a larger acceptance
angle which in turn equates to its ability to gather more light.
SIN θ = NA = (n12 –n0
2)½
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Distance
Optical Parameters - Signal Distortion
Ideal RealisticBad
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Optical Parameters - Dispersion
Standard single mode fiber dispersion curve
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Optical Parameters - Bandwidth
Bandwidth:
The information carrying capacity of fiber•MHz are units for analog transmission•Mb/ps are units for digital transmission
•Specifications are displayed in MHz-km; normalized, not linear
•Bandwidth is directly related to dispersion in multimode fiber•High dispersion causes pulses to overlap, limiting transmission rate•Single mode fiber specifies mode field diameter instead
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Optical Specifications
Notes:
1. Specified attenuation is the maximum for all of the fibers in the cable over the
operating temperature range.
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Fiber Manufacturing
3 Steps in Fiber Manufacturing
•Laydown (Deposition)
•Consolidation
•Draw
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Fiber Manufacturing - Deposition
Outside Vapor Deposition Process (OVD)
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Fiber Manufacturing - Drawing
The speed of the draw determines the
diameter of the glass fiber
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
The National Electric Code - Definitions
• The NEC is advisory in nature
• It must be (and has been) adopted by each state
• Each state adds its own articles to the code
• Always check with LAHJ
• PLENUM (P) — environmental air space (hung ceilings, raised floors, fan
rooms, ducts)
• RISER (R) — openings through which cable goes vertically from floor to
floor
• GENERAL (G) — all other areas
•Note: Non-rated cables must be terminated within 50 feet of entering a
building.
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Cable Markings: In accordance with NEC Article 770
• OFC Optical Fiber Conductive
• OFN Optical Fiber Non-conductive
• OFCG Optical Fiber Conductive General Purpose
• OFCP Optical Fiber Conductive Plenum
• OFNG Optical Fiber Non-conductive General Purpose
• OFNP Optical Fiber Non-conductive Plenum
• OFCR Optical Fiber Conductive Riser
• OFNR Optical Fiber Non-conductive Riser
• OFN-LS Optical Fiber Non-conductive Low-Smoke
Cable Fire Listings and the NEC
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
(UL) Fire Ratings
UL 910
Test for Flame Propagation and Smoke Density Values
for Electrical and Optical-Fiber Cables Used in Spaces
Transporting Environmental Air
UL 1666
Test for Flame Propagation Height of Electrical and
Optical-Fiber Cables Installed Vertically in Shafts
UL 1581
Vertical Tray Flame Test
Plenum
Riser
General
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
• Safety glasses must be worn at all times when working with bare fiber.
• Laser light can damage your eyes.
• Laser light is not visible - Viewing it directly does not cause pain; the iris of the eye will not close as when viewing a bright light. Consequently, serious damage to the retina of the eye is possible.
• NEVER LOOK INTO THE END OF A FIBER WHICH MAY HAVE A LASER COUPLED TO IT.Should eye exposure to laser light be suspected, arrange for an eye examination immediately.
• Cleaved glass fiber is very sharp and can pierce skin easily. Do not let cut pieces of fiber stick to your clothing or drop in the work area where they can cause injury later. Use tweezers to pick up cut or broken pieces of glass fiber and place them on a loop of tape kept for that purpose only, or place directly into collection bin.
• Good housekeeping is very important when working with optical fiber.
Fiber Optic Safety
Proprietary and Confidential © 2013 Amphenol
• Isopropyl alcohol is flammable, with a flash point of 12C. Dispose of
contaminated materials in flame-retardant bin only.
• Isopropyl alcohol can cause irritation to eyes on contact. In case of eye contact,
flush with water for at least 15 minutes. Inhaling fumes can induce mild narcosis. In
case of ingestion consult a physician. Use with adequate ventilation.
• Un-cured epoxy adhesives consisting of resin and hardener components may
cause skin irritation or allergic reactions. Prevent all contact with skin or eyes!
If contact occurs, flush immediately with plenty of water. Avoid heat except during
curing. Avoid prolonged inhalation and use adequate ventilation.
Fiber Optic Safety
Proprietary and Confidential © 2014 Amphenol
ATTENUATION: Where does it occur?
Attenuation occurs in the following components of a
fiber optic system:
FIBER
• along its full length (intrinsic)
• at Macrobends and Microbends (extrinsic)
SPLICES
• at fusion and mechanical splices
CONNECTORS
• at air gaps between mated connectors
37
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2014 Amphenol
CALCULATING A LOSS BUDGETUnderstanding Dynamic Range
Verify end equipment compatibility with system.
-Known as ‘Dynamic Range’
If optical signal is too strong , the receiver floods,
potentially causing long-term damage
If the optical signal is too weak, it cannot be detected once
it reaches the receiver
Look for labels on the back of each piece of equipment for
this information and be sure to adjust the budget accordingly
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
CALCULATING A LOSS BUDGETTo calculate a loss budget for a fiber optic system:
Follow contract specifications first•Contracts often specify maximum allowable losses in the cable, splices, and
connectors. In the absence of such guidelines:
Refer to industry measurement standards (i.e. EIA/TIA 568A, which
allows less than 0.10 dB per fusion splice and less than 0.75 dB per
connector pair)
Refer to cable manufacturer specification sheets (industry standard
fiber performance for multimode is 3.5 dB/km @850nm and 1.0
dB/km @1300nm; singlemode is 0.4 dB/km @1310nm and 0.3
dB/km @1550nm)
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
CALCULATING A LOSS BUDGETCompute for each operating wavelength (850, 1300 nm for multimode and 1310, 1550, 1625 nm for singlemode)
Maximumallowablesystem
attenuation
+Maximumallowable
fiber attenuation
Maximumallowable
attenuation on all splices
Maximumallowable
attenuation on connector pairs
=
+
Fiber attenuation is measured in dB/km, but cables are measured in
feet or meters. The conversion factors for these measurements are
1000 m = 1 km and 3.282 ft = 1 m.
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Fiber (f iber length) (f iber at tenuat ion) (conversion factor)
_________ ________(f t ) X _________(dB/km) X (1km/3282 f t )
+Splices (# splices) (max at ten/splice)
_________ ___________ X ______________(dB)
+Connectors (# connectors) (max at ten/conn)
_________ ___________ X ______________(dB)
=Total allowed loss budget
CALCULATING A LOSS BUDGETHelpful chart
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2014 Amphenol
Attenuation Testing
The source contains either a light-emitting diode (LED) for multimode systems, or a
laser for singlemode systems. Note: Some higher-speed MM systems now operate
with laser or laser-like sources
The meter, or detector, receives an optical signal (light) at particular wavelengths
and is calibrated to measure the light at each wavelength.
Optical test sets are sold in various port configurations
System Type Source Operating
Wavelengths
Singlemode LASER
1310nm
1550nm
1625nm
Mult imode LED 850nm
1300nm
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
Test Set-upAccording to EIA/TIA 526, system
testing must be done with 2 patch
cords--one between the source and
system, the other between the meter
and system.
Note: Launch and receive cables are
used to protect the test set in case of
faulty or dirty ends.
The connector at the meter end may
be faulty (and may not be detected).
The launch and receive cables are
essentially removed from the test or
zeroed out during referencing
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2013 Amphenol
A one-jumper reference: The ‘Patch Panel to Patch Panel’ System
•The method of system operation is identical to the necessary test set-up (two jumpers).
Therefore, the only power needing removed is the coupled power at the source. Use one
jumper to transfer that power to the meter.
•Keep in mind that the loss in the jumper is not significant--it’s the use of the jumper to
connect and/or transfer optical power that matters.
System Test Reference
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2012 Amphenol
A closer look at the 2-jumper reference
System consists of patching through a panel on one end
and directly connecting to end equipment at the other.
Receive Cable
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2012 Amphenol
A closer look at the 3-jumper reference
3rd Patch Cord
System consists of directly connecting to end equipment
at both ends of the link.
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2014 Amphenol
Optical Time Domain Reflectometer (OTDR)
Optical Time Domain Reflectometer
(OTDR): A measurement device that graphically
depicts attenuation over distance by injecting light at
the source and measuring the amount of
backscattered light over time.
An OTDR can also measure attenuation. It is not,
however, the standard for total system attenuation
measurements, as inherent variations in fiber
geometry can render its results imprecise.
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2012 Amphenol
When is an OTDR useful?
OTDR Applications include:
Continuity testing: quickly verify that cable/system has no breaks
(sometimes called on-the-reel testing)
Troubleshooting: identify location of faults in a system
Documentation: provide the customer with proof of a quality fiber
optic installation and give them reference for future moves, adds,
changes
Connector loss measurements: measure loss across individual
connector pairs, especially at installation
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2012 Amphenol
Understanding OTDR displays
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2014 Amphenol
Comparing OTDRs and Optical Test Sets
Function
OTDR
Test Set
Fault Locating
Yes
No
End-to-end
attenuation test
Estimate only
Yes
Connector Pair
testing
Yes
Yes
Length
Measurement
Yes
No
Fiber Optic Basics & Terminology
Proprietary and Confidential © 2014 Amphenol
There are four types of cleaning methods used for fiber optic connectors:
• Dry cleaning: Cleaning without the use of any solvents.
• Wet cleaning: Optic cleaning with solvents. Typically IPA (isopropyl alcohol).
• Non-Abrasive cleaning: Cleaning without abrasive material touching the fiber optic connector end face. Examples are air dusters or pressured solvent jet used in automated connector cleaners.
• Abrasive cleaning: The popular lint free wipes, reel based Cletop fiber connector cleaners and optic cleaning swabs such as the Cletop sticks are all abrasive cleaning types.
Fiber Optic Cleaning
Proprietary and Confidential © 2014 Amphenol
Tools and products:
• Air dusters are used to blow loose particles from optical fiber connector end face, or dry up solvent (isopropyl alcohol) residue after a wet cleaning. All air dusters are not the same. Optic grade is more expensive. Air spray is a non-abrasive fiber optic cleaning method.
• Wet/Dry lint-free swabs – used one time only first wet, then dry to remove debris and solvents from the fiber end face.
• Semi-Abrasive Cloth cleaning tools such as the Cletops cleaner and stick style cleaners that advance a lint-free cloth to clean the end face.
Fiber Optic Cleaning
Proprietary and Confidential © 2014 Amphenol
Tools and products:
• Inspection Scopes are used to view the end face of the optical connector indirectly preventing eye damage and giving a very clear picture of the state of the end face. Will show dirt & debris as well as damage and scratches.
Fiber Optic Inspection