Fiber Optics Technology

Introduction to Optical Fibers.

Fibers of glassUsually 120 micrometers in diameterUsed to carry signals in the form of light over distances up to 50 km.No repeaters needed.

Introduction (Cont…)

Core – thin glass center of the fiber where light travels.Cladding – outer optical material surrounding the coreBuffer Coating – plastic

coating that protects the fiber.

Evolution of Fiber1880 – Alexander Graham Bell1930 – Patents on tubing1950 – Patent for two-layer glass wave-guide1960 – Laser first used as light source1965 – High loss of light discovered1970s – Refining of manufacturing process1980s – OF technology becomes backbone of long distance telephone networks in NA.

Advantages of Optical Fibre

ThinnerLess ExpensiveHigher Carrying CapacityLess Signal Degradation& Digital SignalsLight SignalsNon-FlammableLight Weight

Areas of Application

TelecommunicationsLocal Area NetworksCable TVCCTVOptical Fiber Sensors

Type of Fibers

Optical fibers come in two types:Single-mode fibers – used to transmit one signal per fiber (used in telephone and cable TV). They have small cores(9 microns in diameter) and transmit infra-red light from laser.Multi-mode fibers – used to transmit many signals per fiber (used in computer networks). They have larger cores(62.5 microns in diameter) and transmit infra-red light from LED.

How Does Optical Fibre Transmit Light??

Total Internal Reflection.Fibre Optics Relay Systems has

-Transmitter-Optical Fibre-Optical Regenerator-Optical Receiver

Total Internal Reflection in Fiber

How are Optical Fibre’s made??

Three Steps are Involved-Making a Preform Glass Cylinder-Drawing the Fibre’s from the preform-Testing the Fibre

Testing of Optical Fiber

Tensile StrengthRefractive Index ProfileFiber GeometryInformation Carrying CapacityOperating temperature/humidity rangeAbility to conduct light under waterAttenuation

Optical Fiber LayingMechanical Linking

Includes coupling of two connectors end to endOptical distribution frames allow cross connect fibers from by means of connection leads and optical connectorsSoldering:

• This operation is done with automatic soldering machine that ensures:

– Alignment of fiber’s core along the 3 axis– Visual display in real-time of the fibers soldering– Traction test after soldering (50 g to 500 g)

Optical Fiber Laying (Cont…)

Blowing Used in laying optical cables in roadways.Cables can be blown in a tube high density Poly EthyleneOptical fiber is then blown in the tube using an air compressor which can propel it up to 2 kilometers away.

Tools of TradeCleaning fluid and ragsBuffer tube cutterReagent-grade isopropyl alcoholCanned airTape (masking or scotch)Coating stripMicroscope or cleaver checkerSplicerConnector supplies

Fiber Optics Test KitFeatures

Includes Smart FO Power Meter and Mini LED or laser sourceFO test lite software for data loggingTests all networks and cable plantsNew versions of Gigabit EthernetLow Cost

ApplicationsMeasure optical power or loss Trouble shooting networks

Protecting FibersTougher than copper wiresDesigned in three concentric layersCore – Cladding – Buffer

Two basic buffer types• Tight buffer• Loose tubes

Implementation of Different LANsIEEE 802.3

FOIRL• Fiber optic inter repeater link• Defines remote repeaters using fiber optics• Maximum length – 1000 meters between any

two repeaters.

IEEE 802.3 (Cont…)10BASEF• Star topology with hub in the center• Passive hub:

– Short cables – No cascading – Reliable

• Active hum:– Synchronous– May be cascaded– Do not count as one repeater– Any 10BASEF active hub must have at

least two FOIRL ports

Token Ring

Advantages Long rangeImmunity to EMI/RFIReliabilitySecurity Suitability to outdoor applicationsSmall sizeCompatible with future bandwidth requirements and future LAN standards

Token Ring (Cont…)

DisadvantagesRelatively expensive cable cost and installation costRequires specialist knowledge and test equipmentNo IEEE 802.5 standard published yetRelatively small installed base.

Fiber Distributed Data Interface

Stations are connected in a dual ringTransmission rate is 100 mbpsTotal ring length up to 100s of kms.

Conclusion

This concludes our study of Fiber Optics. We have looked at how they work and how they are made. We have examined the properties of fibers, and how fibers are joined together. Although this presentation does not cover all the aspects of optical fiber work it will have equipped you knowledge and skills essential to the fiber optic industry.