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A System view of Optical Fiber Communication. Prepared by. Ismail Ali Al-Qaram. Zeyad Al-Qabbani. Ali Kamel Al-Awami. Overview:. An optical fiber is a glass or plastic fiber designed to guide light along its length by total internal reflection.

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A System view of Optical Fiber Communication

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A system view of optical fiber communication

A System view of

Optical Fiber Communication


A system view of optical fiber communication

Prepared by

Ismail Ali Al-Qaram

Zeyad Al-Qabbani

Ali Kamel Al-Awami


A system view of optical fiber communication

Overview:

An optical fiber is a glass or plastic fiber designed to guide light along its length by total internal reflection

Optical fibers are widely used in fiber-optic communication, which permits digital data transmission over longer distances and at higher data rates than electronic communication.


A system view of optical fiber communication

History

Optical fiber was developed in 1970 by Corning Glass Works with attenuation low enough for communication purposes (about 20dB/km)

  • 1st generation operated at a wavelength 0.8 µm

  • 2nd generation 1.3µm

  • 3rd generation 1.55µm

  • 4th generation 1.6µm

  • 5th generation extending the wavelength range over which a WDM system can operate.


A system view of optical fiber communication

Types of optical fiber:

  • SINGLE-MODE FIBER

  • - narrow core, diameter (8 microns or less).

  • - Light travels parallel to the axis.

  • - little pulse dispersion.

  • Uses:

  • Telephone & cable television networks


A system view of optical fiber communication

  • STEP-INDEX MULTIMODE FIBER

- large core, diameter: 100 microns

- travel in direct route, other rays zigzag as they bounce off the cladding

- pulse, spread out, losing its well-defined shape

  • Uses:

  • short distances, for example an endoscope


A system view of optical fiber communication

  • GRADED-INDEX MULTIMODE FIBER

- core has refractive index that diminishes gradually from the center axis out toward the cladding.

- the light rays move down the axis advance more slowly than those near the cladding.

- light in the core curves helically.

- shortened path & higher speed less dispersion.


A system view of optical fiber communication

Comparison


A system view of optical fiber communication

BASIC CABLE DESIGN

  • Two basic cable designs:

  • 1- Loose-Tube Cable:

  • Uses:

  • - used in outside-plan installations.

  • Properties:

- holds up to 12 fibers per buffer tube.

- fibers are loosely packaged in gel filled buffer tubes to repel water.

- endure outside temperatures and high moisture.

- Typically, distance not to exceed 50 feet.


A system view of optical fiber communication

2-Tight-Buffered Cable

  • Uses:

- often used for intra-building

  • Properties:

  • no gel, connectors terminated directly onto the fiber without difficult to use breakout kits

  • less expensive installation

- (Temperature rating -40ºC to +85ºC).

- Typically, long distance


A system view of optical fiber communication

Communication Applications

  • Fiber-optic cable is used by many telecommunications companies to transmit telephone signals, internet communication, and cable television signals, sometimes all on the same optical fiber


A system view of optical fiber communication

Communication System Using Optical Fiber

  • Components of the Transmission System:

  • Transmitters

  • Amplifiers

  • Receivers


A system view of optical fiber communication

  • Transmitters:

- The most commonly used optical transmitters are semiconductor devices such as Light emitting diodes (LEDs) and laser diodes.

- A semiconductor laser emits light through stimulated emission rather than spontaneous emission

high output power (~100 mW)

- efficiency (~50%)

LEDs:

- wide spectral width of 30-60 nm

- Output power 100 microwatts

- efficiency (~1%)

laser diodes:

- wide spectral width of0.81-0.87 µm

- High data rates, long distances


A system view of optical fiber communication

  • Amplifiers:

- Solution for fiber attenuation and fiber distortion.

- amplifies the optical signal directly without having to convert the signal

into the electrical domain.

- Made by doping a length of fiber with an rare-earth mineral (erbium), and pumping it with light from a laser with a shorter wavelength than the communications signal (typically 980 nm)

  • Recivers:

- The main component of an optical receiver is a photo detector that converts light into electricity through the photoelectric effect.

- detectors are also used due to their suitability for circuit integration in regenerators and wavelength-division multiplexers


A system view of optical fiber communication

Wavelength-Division Multiplexing (WDM) :

  • WDM is dividing the wavelength capacity of an optical fiber into multiple channels.

  • Requirements:

  • - multiplixer in the transmition.

  • - demultiplexer in the receiving.

  • bandwidth can be divided up to 80 channels

  • - carry information at around 14 Terabits/s over 160 km of fiber.


A system view of optical fiber communication

Attenuation

  • - attenuation is caused by a combination of material absorption, and connection losses.

  • attenuation in modern fiber is

  • about 1000 db/km.

  • - other causes of attenuation are physical stresses to the fiber, microscopic fluctuations in density, and imperfect splicing techniques.


A system view of optical fiber communication

Comparison between electrical transmission

and fiber optics


A system view of optical fiber communication

THE END

Thanks for listening


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