opto1st

BENCHMARK

FIBER OPTICS BASICS

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BENCHMARK

FIBER OPTICS BASICS

BENCHMARK

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: [email protected]

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: [email protected]