Introduction to Optical Fibers. • Fibers of glass • Usually 120 micrometers in diameter • Used 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 core • Buffer Coating – plastic coating that protects the fiber.
Evolution of Fiber • 1880 – Alexander Graham Bell • 1930 – Patents on tubing • 1950 – Patent for two-layer glass wave-guide • 1960 – Laser first used as light source • 1965 – High loss of light discovered • 1970s – Refining of manufacturing process • 1980s – OF technology becomes backbone of long distance telephone networks in NA.
Advantages of Optical Fibre • Thinner • Less Expensive • Higher Carrying Capacity • Less Signal Degradation& Digital Signals • Light Signals • Non-Flammable • Light Weight
Areas of Application • Telecommunications • Local Area Networks • Cable TV • CCTV • Optical 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
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 Strength • Refractive Index Profile • Fiber Geometry • Information Carrying Capacity • Operating temperature/humidity range • Ability to conduct light under water • Attenuation
Optical Fiber Laying • Mechanical Linking • Includes coupling of two connectors end to end • Optical distribution frames allow cross connect fibers from by means of connection leads and optical connectors • Soldering: • 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 Ethylene • Optical fiber is then blown in the tube using an air compressor which can propel it up to 2 kilometers away.
Tools of Trade • Cleaning fluid and rags • Buffer tube cutter • Reagent-grade isopropyl alcohol • Canned air • Tape (masking or scotch) • Coating strip • Microscope or cleaver checker • Splicer • Connector supplies
Fiber Optics Test Kit • Features • Includes Smart FO Power Meter and Mini LED or laser source • FO test lite software for data logging • Tests all networks and cable plants • New versions of Gigabit Ethernet • Low Cost • Applications • Measure optical power or loss • Trouble shooting networks
Protecting Fibers • Tougher than copper wires • Designed in three concentric layers • Core – Cladding – Buffer • Two basic buffer types • Tight buffer • Loose tubes
Implementation of Different LANs • IEEE 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 range • Immunity to EMI/RFI • Reliability • Security • Suitability to outdoor applications • Small size • Compatible with future bandwidth requirements and future LAN standards
Token Ring (Cont…) • Disadvantages • Relatively expensive cable cost and installation cost • Requires specialist knowledge and test equipment • No IEEE 802.5 standard published yet • Relatively small installed base.
Fiber Distributed Data Interface • Stations are connected in a dual ring • Transmission rate is 100 mbps • Total 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.