OPTICAL FIBRES

Amyn Charaniya Roxanne Fernandes Jaydeep Mehta Roshani Shah

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History

Fibre optics, though used extensively in the modern world, is a fairly simple and old technology. It was first demonstrated by Daniel Colladon and Jacques Babinet in Paris in the early 1840s. Practical applications, such as close internal illumination during dentistry, appeared early in the twentieth century.

What are Optical Fibres

?

Optical Fibres are fibres of glass, usually about 120 micrometers in diameter, which are used to carry signals in the form of pulses of light over distances up to 50 km without the need for repeaters. These signals may be coded voice communications or computer data

Long thin strands of very pure glass about the size of human hair

Arranged in bundles called optical cables

Used to transmit light signals over long distances Hundreds of thousands arranged in bundles to form optical cables

An optical fibre is a waveguide for light

consists of : core cladding buffer jacket inner part where wave propagates outer part used to keep wave in core protective coating outer protective shield

The optical fibre can be used as a medium for telecommunication and networking because it is flexible and can be bundled as cables. In telecommunications applications, the light used is typically infrared light Fibres are generally used in pairs, with one fibre of the pair carrying a signal in each direction Fibres, like waveguides, can have various transmission modes. The fibres used for long-distance communication are known as single mode fibres, as they have only one strong propagation mode.

Types of optical fibres

Single mode

only one signal can be transmitted use of single frequency

Multi mode

Several signals can be transmitted Several frequencies used to modulate the signal

Typical core and cladding diametersType Core (mm) Single mode 8 Multimode 50 Cladding (mm) 125 125

62.5

125

100

140

Fibre can be bent!!

Areas of Application

Telecommunication

Optical fibres are now the standard point to point cable link between telephone substations.

Local Area Networks (LAN)

Multimode fibre is commonly used as the "backbone" to carry signals between the hubs of LAN's from where copper coaxial cable takes the data to the desktop. Can support hundreds of stations on a campus

Areas of Application Cable TV

As mentioned above domestic cable TV networks use optical fibre because of its very low power consumption.

CCTV

Closed circuit television security systems use optical fibre because of its inherent security.

Areas of Application Long-haul trunks

Metropolitan trunks -to join phone exchanges in metro areas Rural exchange trunks -connect exchanges of different phone companies

-common in telephone networks

Other Applications

Advantages of Optical Fibres

Can carry much more information Much higher data rates Much longer distances than co-axial cables Immune to electromagnetic noise Light in weight Unaffected by atmospheric agents

Disadvantages of Optical Fibres Expensive Need to convert electrical signal into optical signal when transmitting and convert it back to electrical signal when receiving

Conclusion Fibre optic is the best choice in terms of speed, bandwidth and security. It is better than a co-axial cable. One should always opt for an optic fibre cable since it reduces data loss and has a high data transmission rate even though it is a little more expensive than coaxial cable.

Thank You