Specifying Optical Fiber Specifying Optical Fiber CableCable

Cable Parameters and Cable Parameters and Typical ValuesTypical Values

Installation v. Environmental Installation v. Environmental SpecificationsSpecifications

Installation SpecificationsInstallation Specifications• Ex: Installation Load (Pulling force)Ex: Installation Load (Pulling force)

Environmental SpecificationsEnvironmental Specifications• Determine the cable’s long-term Determine the cable’s long-term

performanceperformance• Ex: Temperature range of operationEx: Temperature range of operation

Installation SpecificationsInstallation Specifications

Maximum installation loadMaximum installation load• Force in lb. (or kg-force or N)Force in lb. (or kg-force or N)• Pulling with more than this force will Pulling with more than this force will

permanently change the attenuation of permanently change the attenuation of the fiberthe fiber

• Typical values:Typical values: 67-125 lb. for 1-fiber cables67-125 lb. for 1-fiber cables 250-500 lb. for cables with 6-12 fibers250-500 lb. for cables with 6-12 fibers 600 lb. for self-supporting aerial cables600 lb. for self-supporting aerial cables

Installation SpecificationsInstallation SpecificationsMinimum installation bend radiusMinimum installation bend radius

• Don’t bend the cable Don’t bend the cable under tension under tension through a corner sharper than thisthrough a corner sharper than this

• If you violate the bend radius, you may If you violate the bend radius, you may damage some part of the cable damage some part of the cable structurestructure

• Typical value: 20 times cable diameterTypical value: 20 times cable diameter

Installation SpecificationsInstallation Specifications

DiameterDiameter• Important when fitting the cable into a Important when fitting the cable into a

crowded conduitcrowded conduit

Temperature range for installation Temperature range for installation and storageand storage

Environmental Environmental SpecificationsSpecifications

Temperature rangeTemperature range• Outside this range, the plastic may Outside this range, the plastic may

crack, orcrack, or• Expansion cycles will create Expansion cycles will create

microbends in the fiber, increasing microbends in the fiber, increasing attenuationattenuation

Indoor, typically -10 to 50 CentigradeIndoor, typically -10 to 50 Centigrade Outdoor, typically -20 to 60 CentigradeOutdoor, typically -20 to 60 Centigrade Military: -55 to 85 CentigradeMilitary: -55 to 85 Centigrade

• Image: a Teflon-coated fiber optic thermometer Image: a Teflon-coated fiber optic thermometer that operates down to 5 degrees Kelvin (link Ch that operates down to 5 degrees Kelvin (link Ch 5i)5i)

Environmental Environmental SpecificationsSpecifications

Minimum long-term bend Minimum long-term bend radiusradius

• With the cable not under tensionWith the cable not under tension• Typically 10 diametersTypically 10 diameters

Image: Japanese fiber with bend radius Image: Japanese fiber with bend radius under 1 cm (link Ch 5h)under 1 cm (link Ch 5h)

NEC (National Electrical Code)NEC (National Electrical Code)• Three cable fire ratings:Three cable fire ratings:

No letter or G: General use—least No letter or G: General use—least stringent fire teststringent fire test

R: Riser—can be used in vertical shaftsR: Riser—can be used in vertical shafts P: Plenum—most strict testP: Plenum—most strict test

Environmental SpecificationsEnvironmental Specifications

Long-term use loadLong-term use load• Important for long vertical installationsImportant for long vertical installations• Aerial installationAerial installation

Vertical rise distanceVertical rise distance• Must put in strain-relief loopsMust put in strain-relief loops

Flame resistanceFlame resistance• Non-building applicationsNon-building applications

UV stabilityUV stability

Environmental SpecificationsEnvironmental Specifications

Resistance to Rodent DamageResistance to Rodent Damage• Inner ducts are an alternative to armorInner ducts are an alternative to armor

Steel armorSteel armor Copper tape armorCopper tape armor Braided armorBraided armor Dielectric armorDielectric armor

• Image from arcelect.comImage from arcelect.com

• Armor makes the cable much less Armor makes the cable much less flexibleflexible

Environmental SpecificationsEnvironmental Specifications

Resistance to water damageResistance to water damage• Filled and BlockedFilled and Blocked

Each loose buffer tube is filled (with gel or Each loose buffer tube is filled (with gel or tape)tape)

A blocking material fills the space between A blocking material fills the space between the tubesthe tubes

Crush loadCrush load• Short-term v. long-termShort-term v. long-term

Environmental SpecificationsEnvironmental Specifications

Abrasion resistanceAbrasion resistance Resistance to chemicalsResistance to chemicals

Environmental SpecificationsEnvironmental Specifications

Resistance to conduction under Resistance to conduction under high voltagehigh voltage

ToxicityToxicity• ““Halogen-free” cables produce less Halogen-free” cables produce less

harmful smokeharmful smoke• Required in Japanese and European Required in Japanese and European

buildingsbuildings High flexibilityHigh flexibility

• If constantly bending, like an elevatorIf constantly bending, like an elevator

Environmental SpecificationsEnvironmental Specifications

Hermetically sealed fiberHermetically sealed fiber• Protect it from water pressure, etc.Protect it from water pressure, etc.

Radiation resistanceRadiation resistance• Nuclear reactors or satellitesNuclear reactors or satellites

Impact ResistanceImpact Resistance• Dropping heavy objects on the cableDropping heavy objects on the cable

Gas permeabilityGas permeability• Preventing gas from escaping through Preventing gas from escaping through

the cablethe cable

Environmental SpecificationsEnvironmental Specifications

Stability of filling compoundsStability of filling compounds• Temperature cycles can pump filling Temperature cycles can pump filling

compounds out the end of the cablecompounds out the end of the cable VibrationVibration

Design ShortcutsDesign Shortcuts

Future-Proofing a SystemFuture-Proofing a System

Include extra fibers in cablesInclude extra fibers in cables• It costs very little more to get a cable It costs very little more to get a cable

with more fibers in itwith more fibers in it Include singlemode fibers in Include singlemode fibers in

multimode cablesmultimode cables• Allows enormous bandwidth increases Allows enormous bandwidth increases

laterlater Use dual-wavelength multimode fiberUse dual-wavelength multimode fiber

• Or even laser-optimized fiberOr even laser-optimized fiber

Multimode FibersMultimode Fibers

Early multimode systems used Early multimode systems used 62.5/125 micron fiber62.5/125 micron fiber• LED light sources at 850 or 1300 nmLED light sources at 850 or 1300 nm• 10 Mbps or 100 Mbps10 Mbps or 100 Mbps• Huge installed baseHuge installed base

50/125 micron fiber50/125 micron fiber• Faster with VCSEL sources at 850 nmFaster with VCSEL sources at 850 nm

Laser-optimized 50/125 micron fiberLaser-optimized 50/125 micron fiber• Fastest, using VCSEL sourcesFastest, using VCSEL sources

Singlemode Fibers Singlemode Fibers

Usually 1300 nm singlemode fiber is Usually 1300 nm singlemode fiber is good enoughgood enough

Cheaper than 1550 nm or two-Cheaper than 1550 nm or two-wavelength systemswavelength systems

Cable TypesCable Types

IndoorIndoor• Short distance – Break-out cableShort distance – Break-out cable• Longer distance – Distribution cableLonger distance – Distribution cable• Rugged environment – Break-out cableRugged environment – Break-out cable• Use all-dielectric cableUse all-dielectric cable• Plenum-rated PVC is recommendedPlenum-rated PVC is recommended

Cable TypesCable Types

OutdoorOutdoor• Cable should be water-blocked and gel-Cable should be water-blocked and gel-

filledfilled• Many fibers (>36) – consider ribbon Many fibers (>36) – consider ribbon

cablecable• For midspan access, use stranded loose-For midspan access, use stranded loose-

tube cabletube cable• Use all-dielectric cableUse all-dielectric cable

Stranded Loose-TubeStranded Loose-Tube Same as loose-tube tableSame as loose-tube table

• Image from Corning (Link Ch 5f)Image from Corning (Link Ch 5f)

Cable TypesCable Types

Indoor/OutdoorIndoor/Outdoor• You could splice You could splice

indoor to indoor to outdoor at the outdoor at the building building entranceentrance

• Or use indoor-Or use indoor-outdoor cable outdoor cable like Corning’s like Corning’s FREEDMFREEDM

• Image from Corning Image from Corning (Link Ch 5g)(Link Ch 5g)

Cable and Source PricesCable and Source Prices

Not in textbookNot in textbook

History of EthernetHistory of Ethernet

From Corning (link Ch 5b)From Corning (link Ch 5b)

SourcesSources

From Corning (link Ch 5b)From Corning (link Ch 5b)

Cable PricesCable Prices

For 500 feet of riser-rated indoor bulk For 500 feet of riser-rated indoor bulk cable, 12-fibercable, 12-fiber• 62.5/125 micron MM62.5/125 micron MM $889$889• 50/125 micron MM 50/125 micron MM $889$889• 50/125 micron50/125 micron

laser-optimized MM laser-optimized MM $1143$1143• 8.5/125 micron SM8.5/125 micron SM $584$584

From blackbox.com (link Ch 5c)From blackbox.com (link Ch 5c)

Media Converter PricesMedia Converter Prices

100 Mbps Multimode:100 Mbps Multimode: $ 229$ 229 1 Gbps Multimode:1 Gbps Multimode: $ 760$ 760 1 Gbps Singlemode:1 Gbps Singlemode: $1,180$1,180

• Prices from L-Com.com (Links Ch 5d & 5e)Prices from L-Com.com (Links Ch 5d & 5e)