The Gift of Optical Fibre Communication
to Modern Life
(Dr.Taran Kumari
Roy, Muzaffarpur, India)
The advancement of Medical
Science, Development of many instruments, Equipments
for modern life to be comfortable was and is, and will
always be dependent on the progress of Electronic and
computer technology. It is essential for the academicians,
scientists and engineers, student of science technology
to develop their interests and exchange their technical
knowledge and enhance their communication and presentation
skill for the development and redefine the course of
science and Technology of the society.
On the eve of seminar on the well famous topic of today
since “Symposium on Contemporary electronics and
computer Technology’’, I am going to throw
some light on the topic ‘The Gift of Optical Fibre
Communication to Modern Life.’
Optical Fibres are the hair like very fine glass fibres
inside which the light signals can travel. Actually
they act for light frequencies, as wave guides act microwaves,
but they have advantages over wave guides. Optical frequencies,
being of the order of 1015 Hz are much greater than
microwaves (1010 Hz) so light beams when used as a carrier
wave for sendug information, is capacity of an optical
fibre is much greater than microwave systems. In other
word multiple routes may be compressed in a much smaller
cable. The basis material for glass fibre is silicon
dioxide which is quite abundant on the Earth. The fibre
cables are strong and flexible; they have smaller and
lighter weight. They do not break even if wrapped in
curves of very small radius. This helps on their transportation
and installation.
Techniques have been developed for the production of
fibres with very low transmission losses about 0.2db/km.
The most important advantage of fibres, they have ability
to carry large amount of information in either digital
&analog form. In a recently developed fibre optic
system, it has been possible to send 140Mbits/sec.Information
through a 220 km link of one optical fibre which is
equivalent to about 4,50,000 voice channel-km.Band width
of optical fibre which is equivalent wire transmission
line. The number of signals that can be modulated on
a fibre optical light beam exceeds the number that can
be modulated on a very high frequency R.F carrier by
a factor about 1000. Optical fibreglass or plasters
are due to external radiator striking the fibre. The
fibre is well protected from interference and not radiate
energy within them; therefore it is difficult to detect
the signal being transmitted. As such they offer a degree
of Security and Privacy.
Optical fibre are extensively used in telecommunications,
surgical operation etc.great progress has been made
in making optical fibres which can guide light, and
thus transmit images round corners. This fibre is used
in endoscopy to examine the internal human organs.
In 1868 oesophascope and gastro scopes (half meter
long pipe fitted with a light and lenses) were introduced.
Light conduction was a formidable obstacle for endoscopes.
It was solved when transmission along aligned bundles
of specially coasted flexible glass fibres was achieved
by H.H.Hopkins & Kapany NS-A flexible fibre scope,
using static scanning. Nature (Lond) vol.173 p 39-41
1954. In 1954 Hopkins and Kapany summarise of their
achievement and introduced new terminology an optical
until comprises a bundle of fibres of glass or other
transpararent materials, and it therefore appears approximate
to introduce the term ‘Fibrescope’ to denote
it. An ovious use of the until is to replace the train
of lenses employed conventional endoscopes.
At present, endoscope some with electronic devices
like video, are used extensively for both diagnostic
and therapeutic purpose. Many more ingenious developments
and applications of the technology are currently at
the point availability viz. wireless capsule endoscopy
foe examination of the small bowel. High magnification
endoscope for detection of minute lesions and confocal
microscopy to obtain histrogical at endoceopy. Everyman’s
Science (vol.XL.No .3 Aug. Set. 2005).
The optical fibres can carry light along curved paths
by the process of total internal reflection of the light
and hence transmit images round the corners. Optical
fibre are being used a technique called ‘endoscopy’
to examine the human body organs. This also helps in
conducting surgical operations. Optical fibre is being
used in telecommunications like telephones. An optical
cable cans hundreds of telephone conversation through
it at the same time.
The emitter is usually on LED or semiconductor laser.
Whilst the detector may be a pin or avalanche photodiode.
Repeater until may be necessary over relative long links
to counter the effects of fibre transmission losses
and dispersion. In these, the signal is detected, amplified
and then re-emitted. For digital signal it is possible
to restore distorted digital signal pulse to its original
shape, whilst with analog signal distortion or noise
present it, of necessity passed on. A separate power
supply line must be providing for these until. The presence
of repeators greatly adds to the cost of a link.
The main advantage of optical fibre links includes
relatively low attenuation at optimum wavelengths, high
band width (up to several gigahertzes), small physical
size and weight. The elimination of ground loop problems
and immunity from electrical interference. This latter
advantage is especially useful in electrically noisy
environments such as densely populated urban areas and
power stations. There is of course, no spark hazard-an
additional advantage in explosive environments such
as chemical plants. The telephone networks require links
capable of carrying many signal channels simultaneously.
Digital transmission is able to cope with this easily
science the separate bit streams required may be interleaved.
In both the united state and Europe, standard rate have
been agreed upon for various ‘levels’ of transmission.
There are numerous other potential applications including
for example, undersea links, video transmission, computer
links and the military sphere. Missile guidance, several
pilot experiments have been run to examine the feasibility
of providing the whole of community’s communication
information need (such as telephone, T.V., Radio etc)
using fibre opticals.
Thereby my concluding wards I want to state that whole
society should have knowledge about the technology to
develop various uses of optical fibres as its raw materials
are very cheap and easily available.
Reference:-
(i) Opto electrons:-J.Willson JFB Hawkes
(ii) H.H.Hopkins & Kapany N.S.A fexible scope using
static scanning nature (lond)
Vol.173p 39-41.
(iii) Everyman’s science Vol.XL No.3 Aug –
Sept. 2005.
About the Author: Dr. Taran Kumari Roy is Reader
in the University Deptt.of Physics B. R. A. Bihar University,
Muzaffarpur (Bihar)
