Mahmoud Al-Saba – 223132

Majed Al-Bishi – 216423

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History of Fiber Optic Technology People have used light to transmit info. for hundreds of

years The invention of the laser prompted researchers to study

the potential of fiber optics send a much larger amount of data than telephone first experiment letting the laser beam transmit freely in air & through different types of waveguides very large losses in the optical fibers prevented coaxial

cables from being replaced Decrease in the amount of light reaching the end of

the fiber

Cont: History of Fiber Optic Technology

Early fibers had losses around 1,000 dB/km In 1969, several scientists concluded that impurities in the

fiber material caused the signal loss Researchers believed it was possible to reduce the

losses By removing the impurities researchersobserve the improvement In 1970,(corning glass works)* made a multimode fiber with

losses under 20 dB/km. in 1972, the company made a high silica-core multimode

optical fiber with 4dB/km. Nowadays, multimode fibers can have losses as low as 0.5

dB/km at wavelengths around 1300 nm

*company

Introduction Optical fiber has a number of advantages over the copper

wire since it is made glass or plastic

light has a much higher frequency than any radio signal we can generate, fiber has a wider bandwidth To carry more information at one time

Transmitters transmitters include an LED(Light-emitting diodes) or

laser diode

LED produce incoherent light

have relatively large emitting areas and as a result are not as good light source

they are widely used for short distances because they are much more economical

Cont: Transmitters Laser diode produce coherent light used for applications that require the

transmission of signals over long distances Important performance specifications

data rate transmitter rise time wavelength spectral width maximum optical output power

Receivers Receivers are instruments that convert light

into electrical signals.component of an optical receiver is a

photo detector that converts light into electricity

use three types of photodiodespositive-negative (PN) junctionspositive-intrinsic-negative (PIN) photodiodesavalanche photodiodes (APD)

Optical FiberFiber is the medium to guide the light form

the transmitter to the receiver. There are two types:

Multimode FiberSingle-Mode Fiber

Multimode FiberIn multimode fibers more than one light

transmitted at a time.Fiber diameter ranges from 50-to-100

micron.

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Multimode FiberMultimode Fiber is divided into two types:

Multimode Step-index FiberMultimode Graded-index Fiber

Multimode Step-index FiberLights are sent at angles lower than the

critical angle or straightAny light angle exceed the critical angle will

cause it to penetrate through cladding.Obviously light with lower angle will reach

the end faster than others.

Multimode Step-index FiberThe difference in signals receiving time

result in unstable wave light at the receiver.To avoid this problem there should be

spacing between the light pulses but this will limit the bandwidth.

Used for very short distance

Multimode Graded-index FiberIn this mode reduce the problem with

Multimode Step-Index.All the beams reaching the receiver almost at

the same time.This can be done by slowing down the ones

with shorter distance.This is done in fiber implementation by

increasing its refractive index at the center and gradually decreases it toward the edges

Single-Mode FiberOnly one light is transmitted in the fiber.Diameter ranges from 8.3 to 10 microns.It has Higher transmission rate.it can be used for longer distance.

Fiber CablesAdvantages of Cabling fiber:

Ease of HandlingProtectionCrush ResistanceDegradation

Types of Fiber Cables:Loose Tube CableTightly Buffered CableRibbon Cables

Wave Division Multiplexing (WDM)

it is a way to send multiple optical signals from deferent source at the same time on one optical fiber.

Used with single mode fiberHow it works:

At the sender the data stream from each Source is assigned an optical wavelength.

The multiplexer modulates each data stream from each Source.

The resulted optical signal generated for each source data stream is placed on its assigned wavelength.

Wave Division Multiplexing (WDM)

The resulted signals are simultaneously sent through the fiber.

At the receiver the signal is separated into the original signals according to their different wavelengths by using prisms.

These signals are further demodulated.Then, The resulting separated data streams

are provided to the respective Users.

Some ApplicationLong telecommunication systems on land and

at sea to carry many simultaneous telephone calls (or other signals) over long distances.

Links among computers and high resolution video-terminals.

Local area Networks operating at high speeds.

Connections between the telephone N/W and antennas for mobile telephone service.

Interoffice trunks that carry many telephone conversations simultaneously between local and regional switching facilities.

Thank you

Any Question please

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