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Materials and Communications
Optical Fibre Communications
 This
is one of the most exciting technical fields about at the moment
and affects you more than
you realize! This web page will have been sent to you over a
fibre optic link (except, probably, for the last kilometre or so at
your end, which is why you do not notice it!). All your phone calls
(including mobile calls) also travel over fibre optics for most of
the distance between the ends. Without fibre optic communications
you would be stuck with the communications your parents had - no internet,
lots of crackles and VERY expensive (ask them!) - and as for international
calls - you didn't even think about it! (all new transatlantic cables
are fibre).
We can
already cram enough data down one hair-thickness glass fibre to send
all the movies that have ever been made (about 40,000 of them) in
about 20 minutes - and it isn't nearly enough!; demand for new systems
to service a faster internet is huge and still growing fast.
Recent
Developments
Materials
Used
Working
in the industry
Materials
Used
Materials
Used
Materials are important for fibre optics in many ways - firstly of
course for the fibre itself, made of very pure glass deposited from
a chemical reaction in a gas. The fibre is about as transparent
as a light drizzle (this may not sound much but it's remarkable for
anything denser than air, think of the sea or a window viewed through
the edge!). But we also need to generate the light signal and
get the information (like this web page) onto it (called 'modulation')
and for this we use lasers and modulators made from Gallium Arsenide
and similar semiconductors. To work these have to be even purer
than the fibre and they, too, are made using a chemical reaction in
a gas.
Recent
Developments
 The
picture shows in the background a thin wafer of Gallium Arsenide about
75mm in diameter with many modulator patterns on it. When this
is cut up each modulator (see the chip left foreground) can put about
one million phone calls onto a light signal! The internal structure
is very complex and delicate (but not fragile because it is so small)
- the inset shows an electron microscope picture of a metal bridge
a few microns (millionths of a metre) long.
The modulator was made
by Marconi's optical (photonic) business which you can find out more
about from:-
http://www.caswelltechnology.co.uk/
or:-
http://www.marconi.com
For more on the optical fibre itself you could look at the website
for Southampton University's Optoelectronics Research Centre (they
are one of the world-leading groups in this area):-
http://www.orc.soton.ac.uk/
Working in the industry
 BT
Corning
Communications
Marconi
Nortel
Pirelli
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