Fiber Optic Communication

System

Presenter : Saffi Sultan

Purpose of using fiber optic communication

For gigabits and beyond gigabits transmission of data, the fiber optic communication is the ideal choice.

This type of communication is used to transmit voice, video, telemetry and data over long distances and local area networks or computer networks.

It uses light wave technology to transmit the data over a fiber by changing electronic signals into light.

Basic Elements There are three main basic elements of fiber optic communication system. They areCompact light sourceLow loss optical fiberPhoto detector

Accessories like connectors, switches, couplers, multiplexing devices, amplifiers and splices are also essential elements in this communication system.

Compact Light SourceLED and Laser are used as light

sourcesLED for short distance and low

data rate applications.Laser diodes are used of longer

distance and high data rate.Nowadays many improvements

and advancements have made the sources more reliable.

Comparison of LED and Laser diode

Low loss optical fiberParameter like tensile strength,

rigidity, durability should be considered.

Made up of high quality extruded glass (Si) or plastic.

The diameter of the fiber optic cable is in between 0.25 and 0.5mm

Types of optical fibersSingle mode fibers:Transmits one signal per fiberIt is used in telephone and TV sets

Multi mode fibers:Transmits many signals per fiberIt is used in computer and LAN

Photo Detectors:It converts light signal back to an electrical signal.There are two types i) PN photo diode ii) Avalanche Photo diodeComposition of materials vary based on application’s wavelength

(Silicon, Germanium, InGaAs, etc.)

Overview of fiber optic communication

Working:

A fiber optic communication network consists of transmitting and receiving circuitry, a light source and detector devices.

When the electrical signal is given as input, it converts them into light signal with the help of a light source in the transmitter circuitry.

The light beam from the source is carried by a fiber optic cable to the destination circuitry wherein the information is transmitted back to the electrical signal by a receiver circuit.

Receiver Circuit:The receiver circuit consists of a photo detector along with an

appropriate electronic circuit.

The photo detector is capable of measuring magnitude, frequency and phase of the optic field.

Both LED and Laser can be used as light sources based on the application.

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