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2Optical FiberBy: Abidullah Wardak

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4 What is Optical Fiber?

An Optical fiber is a flexible, transparent fiber made of high quality glass (silica) or plastic, slightly thicker than a human hair.

It either functions as a waveguide or light pipe that transmits light between two ends of the fiber or fiber cable.

Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distances and at higher bandwidths (data rates) than other forms of communication

Fibers are used instead of metal wires because signals travel along them with less loss and are also safe to electromagnetic interference.

The field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics.

5 History of Fiber Optics

Fiber optics is not really a new technology, its fairly old.

Guiding of light by refraction, the principle that makes fiber optics possible, was first demonstrated by Daniel Colladon and Jacques Babinet in Paris in the early 1840s

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6 Uses of Optical Fiber

Fiber optic can accommodate variety of needs.

It can be used in Communication, fiber optic sensors, illumination, medical.

And also in other places where bright light needs to be shone on a target without a clear line-of-sight path.

Used in building to route sunlight from the roof to other parts of the building.

And many more usages but we will only discuss use of optical fiber in communication here.

7 In Communication

Optical fiber can be used as a medium for telecommunication and computer networking because it is flexible and can be bundled as cables.

It is especially advantageous for long-distance communications, because light propagates through the fiber with little attenuation compared to electrical cables.

The per-channel light signals propagating in the fiber have been modulated at rates as high as 111 gigabits per second (Gbit/s) by NTT, although 10 or 40 Gbit/s is typical.

 In June 2013, researchers demonstrated transmission of 400 Gbit/s over a single channel.

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Each fiber can carry many independent channels, each using a different wavelength of light.

As of 2011 the record for bandwidth on a single core was 101 Tbit/sec (370 channels at 273 Gbit/sec each).

The record for a multi-core fibre as of January 2013 was 1.05 petabits per second

9 Benefits of Optical Fiber

For short distance application, such as a network in an office building, fiber-optic cabling can save space in cable ducts. This is because a single fiber can carry much more data than electrical cables such as standard category 5 Ethernet cabling, which typically runs at 100 Mbit/s or 1 Gbit/s speeds.

Fiber is also immune to electrical interference; there is no cross-talk between signals in different cables, and no pickup of environmental noise.

Non-armored fiber cables do not conduct electricity, which makes fiber a good solution for protecting communications equipment in high voltage environments, such as power generation facilities, or metal communication structures prone to lightning strikes.

They can also be used in environments where explosive fumes are present, without danger of ignition.

10 Structure of Optical Fiber

Optical fiber is comprised of a light carrying core surrounded by a cladding which traps the light in the core by the principle of total internal reflection.

Most optical fibers are made of glass, although some are made of plastic.

The core and cladding are usually fused silica glass which is covered by a plastic coating called the buffer or primary buffer coating which protects the glass fiber from physical damage and moisture.

There are some all plastic fibers used for specific applications.

Glass optical fibers are the most common type used in communication applications.

11 Modes of propagation Single mode – there is only one path for light to take down the

cable

Multimode – if there is more than one path

Cladding

Cladding

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Structure of single-mode fiber

1. Core: 8 µm diameter

2. Cladding: 125 µm dia.

3. Buffer: 250 µm dia.

4. Jacket: 400 µm dia.

13 Loss in Optical FiberLosses vary greatly depending upon the type of fiber

Plastic fiber may have losses of several hundred dB per kilometerGraded-index multimode glass fiber has a loss of about 2–4 dB per kilometerSingle-mode fiber has a loss of 0.4 dB/km or less

14 What is it made of?

Silica

Plastic

Fluoride

Phosphates

15 Optical fiber cables

In practical fibers, the cladding is usually coated with a tough resin buffer layer, which may be further surrounded by a jacket layer, usually glass. These layers add strength to the fiber but do not contribute to its optical wave guide properties

Modern cables come in a wide variety of sheathings and armor, designed for applications such as direct burial in trenches, high voltage isolation submarine installation, and insertion in paved streets.

Fiber cable can be very flexible, but traditional fiber's loss increases greatly if the fiber is bent with a radius smaller than around 30 mm.

16 Types of Optical fiber cable

Loose Tube Cable

Coated Fiber

Outer Jacket

Steel Tape Armor

Inner Jacket

Aramid Strength Member

Binder

Interstitial Filling

Central Member (Steel Wire or Dielectric)

Interstitial Filling

Loose Tube Cable

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Tight buffered Cable

Glass Fiber

Thermoplastic Overcoating or Buffer

PVC Jacket (Non-Plenum) or Fluoride Co-Polymer Jacket (Plenum)

Fiber Coating

Aramid Strength Member

Tight-buffered Cable

18 Types of Optical fiber cable

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Fiber Connectors

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21 Did you know? A small optical fiber can carry more data than a large copper cable.

It is a unidirectional technology.

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System

ElectricalConnector Electrical

Connector

Transceiver

Transceiver

Fiber Optic Cable

OpticalConnector

OpticalConnector

OpticalPort

OpticalPort

A failure anywhere along this link will cause the entire link to fail

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24 Advantages of Optical Fiber over Conventional Copper System

Broad Bandwidth

Broadband communication is very much possible over fiber optics which means that audio signal, video signal, microwave signal, text and data from computers It is possible to transmit around 3,000,000 full-duplex voice or 90,000 TV channels over one optical fiber.

Electrical Insulator

Optical fibers are made and drawn from silica glass which is nonconductor of electricity and so there are no ground loops and leakage of any type of current. Optical fibers are thus laid down along with high voltage cables on the electricity poles due to its electrical insulator behavior.

 Immunity to Electromagnetic Interference

The optical fiber is electrically non-conductive, so it does not act as an antenna to pick up electromagnetic signals which may be present nearby

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 Low attenuation loss over long distances

There are various optical windows in the optical fiber cable at which the attenuation loss is found to be comparatively low and so transmitter and receiver devices are developed and used in these low attenuation region. Due to low attenuation of 0.2dB/km in optical fiber cables, it is possible to achieve long distance communication efficiently over information capacity rate of 1 Tbit/s.

Lack of costly metal conductor

The use of optical fibers do not require the huge amounts of copper conductor used in conventional cable systems. In recent times, this copper has become a target for widespread metal theft due its value on the scrap market.

26Optical Fiber in Sea

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28Thank YouAbidullah Wardak