Transcript
BENCHMARK
FIBER OPTICS BASICS
BENCHMARK
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BENCHMARK
FIBER OPTICS BASICS
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FIBER OPTICS BASICS
What is Fiber Optics Elements of Fiber Optics Optical Fiber Wavelengths of Operation Optical Devices Optical Connectors Major Advantages Some Practical Disadvantages Major Applications
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WHAT IS FIBER OPTICS
Transmission of data as light pulses through optical fiber(first converting electronic binary signals to light, and then finally converting back to electronic signals)
TRANSMITTER
RECEIVER
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ELEMENTS OF FIBER OPTICS
TRANSMISSION– Light Source (such as Infra Red LED
converts pulses to light pulses and sends into optical fiber)
RECEPTION– Photodetector converts back to electrical
pulses
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PROPAGATION IN FIBER– Light propagates by means of total internal
reflection – Optical fiber consists of two concentric
layers core - inner layer cladding - outer layer
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– Refractive index of core > cladding - necessary for total internal reflection
– Light entering within acceptance angle propagates through fiber
strike core-cladding interface > critical angle and gets reflected completely
zig-zags down length of core through repeated reflections
fairly lossless propagation through bends also
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OPTICAL FIBER
Multimode(Graded Index 50/125micron, 62.5/125micron etc.,)
Single Mode(8.7/125micron)
Propagation of light in a multimode graded index fiber
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OPTICAL FIBER CABLE
LOOSE JACKETED FIBER FIBER CABLE FROM ONE CORE TO
SEVERAL HUNDRED CORES ARMOURED CABLE
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Loose Jacketed Fiber
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Multi-core Fiber Cable
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Armoured Cable
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WAVELENGTHS OF OPERATION
650nm 850nm 1300nm 1500nm (All in infrared wavelength)
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OPTICAL DEVICES
TRANSMITTERS– LEDs
850nm, 1300nm Low cost, easy to use Used for multimode fiber Special ‘Edge-Emitting’ LEDs for single mode
fiber
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– Laser Diodes 850nm, 1300nm, 1550nm Very high power output Very high speed operation Very expensive Need specialized power supply and circuitry
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RECEIVERS– PIN DIODES
850, 1300, 1550nm Low Cost
– APDs (Avalanche Photodiodes) 850, 1300, 1550nm High sensitivity - can operate at very low power
levels Expensive
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OPTICAL CONNECTORS
Commonly Used: SMA, FC, ST, SC– CONNECTORS– RECEPTACLES– ADAPTORS
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MAJOR ADVANTAGES OF FIBER OPTICS
Large Bandwidth (Extremely high information carrying capacity)
Low loss(Long repeaterless link length/repeater spacing)
EMI Immunity(Even in noisy or hard environments - factory floor, high voltage lines)
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Compact & Lightweight Security
(difficult to tap) Safety
(Insulator & no sparks - ideal for hazardous environment)
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SOME PRACTICAL DISADVANTAGES
Fiber is expensive Connectors are expensive
(due to degree of precision involved) Connector installation is time consuming
and require skilled operators Joining (splicing) of fibers requires special
equipment/devices and skilled operators
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Connections & joints are relatively lossy Relatively careful handling required
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MAJOR APPLICATIONS
TELECOM ISDN FACTORY AUTOMATION SENSORS NETWORKS - LANs, WANs
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DEFENCE– BUILDINGS– ON-BOARD COMMUNICATIONS
RAILWAYS
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SINGAPORE:
BENCHMARK SYSTEMS (S) PTE. LTD.
Tel: 65 - 749 - 3372
Fax: 65 - 749 - 3326
E-mail: benchmrk@singnet.com.sg
INDIA:
BENCHMARK ELECTRONIC SYSTEMS (P) LTD.
Tel: 91 - 44 - 413866, 491 0054
Specifications subject to change without notice Fax: 91 - 44 - 491 0123
Copyright © 1996 E-mail: benchmrk@md2.vsnl.net.in