Skip to main content

Why optical fibres are used?

Image
By
∆∆Optical fibre links are being increasingly used for both short-distance communications, such as for local area networks (LANs), and long-distance communications. This arises from the fundamental advantages of optical f ibre communications: 
• They are low cost. 
• They are robust when packaged. 
• They can have very wide optical bandwidths (GHz) and long communication links (hundreds of kilometres).
 • They are insensitive to electromagnetic interference. 

∆∆This has led to the wide range of intercontinental communication links which are several thousand kilometres long, which distance considerably exceeds the maximum length of optical fibre that can be manufactured. It also exceeds the maximum link length over which an optical signal can be propagated without periodic amplification or regeneration. The environment is also somewhat harsh and remote, requiring high reliability and robust packaging.
∆∆The highest frequency was of the order of 1000 GHz. If the frequency is increased to about 1015 Hz, we would find that the signal would literally appear as visible light. Signals in the range 1012–1015 Hz appear as infra-red light, whereas those in the range 1015–1017 Hz appear as ultraviolet light. This raises the question, if we can transmit data using the lower frequency ranges, why should we not communicate at the higher light frequencies? In fact, there is no reason why we should not, but there are difficulties in taking the light from a source to some form of receiving unit within which the carrier could be separated from the basic information signal. There are plenty of materials, such as glass, through which we can pass light. A glass fibre would make a simple conductor of light. The problem is to retain the light within the glass, but it is possible by simple conductor of light. The problem is to retain the light within the glass, but it is possible by simply placing the f ibre within a cladding.
Labels:

Comments

Post a Comment

Popular posts from this blog

How Energy conversion from coal is done?

By
Single generator sets of over 600 MW are now used in the UK, though there are many smaller generators in use. A 600 MW generator can supplythe average needs of over 1 million UK households. Three or four such generators are typically installed in a single large coal-fired station which isoften sited close to a coal mine, away from the city dwellers who consume the electricity. Such generators are usually driven by a compound arrangement of highpressure, intermediate-pressure and low-pressure turbines, increasing in size as the pressure decreases. Modern turbines rotate in a speed range from 1500 to 3500 r.p.m., usually 3000 r.p.m. for the UK’s 50 Hz system. For large coal-fired plant the steam pressure could be 25 megapascals (MPa) with steam temperatures of 500–600 °C to improve the thermodynamic efficiency. In nuclear reactors, which operate under less demanding conditions, the steam is superheated to about 5 MPa and 300 °C. Modern water tube boilers are complex and have ...
Post a Comment
Read more

How Bulletproof glass works?

By
Shattering the science behind what makes the breakable unbreakable Bullet-resistant glass works by absorbing a bullet’s kinetic (movement) energy and dissipating it across a larger area. Multiple layers of toughened glass are reinforced with alternated layers of polycarbonate – a tough but fl exible transparent plastic which retains the see-through properties of glass. As a bullet strikes the fi rst glass layer, the polycarbonate layer behind it forces the glass to shatter internally rather than outwards.  This process absorbs some of the bullet’s kinetic energy. The high velocity impact also fl attens the bullet’s head. Imagine trying to pierce through a sheet of cotton with the top end of a pencil. It would be very diffi cult compared to using the sharp pointed end. The same principle applies here. The fl at-headed bullet struggles to penetrate the layer of polycarbonate. As the bullet travels through each layer of glass and polycarbonate, the process is repeated until it no l...
Post a Comment
Read more

How Coal mining is done?

By
Coal miners literally move mountains to feed our insatiable appetite for cheap energy There’s something brutally simple about coal mining. Take away the monstrous new machinery and ecofriendly marketing jargon and it’s the same dirty, dangerous job it’s always been: fi nd the black stuff and dig it up. The two major schools of coal mining are surface mining and underground mining. To qualify for surface mining, the coal seam must lie within 60 metres of the surface. The miners’ job is to remove all of the ‘overburden’ – the cubic tons of rock, soil and trees above the coal seam – and expose the coal layer for extraction. The main tools of the trade are dynamite and dragline excavators, 2,000-ton behemoths that can move 450 tons of material with one swoop of their massive buckets. Perhaps the most dramatic and controversial surface mining technique is Mountaintop Removal (MTR), in which miners use explosives and heavy machinery to literally knock the top off a mountain – up to 200 ...
Post a Comment
Read more