Mahmoud Al-Saba – 223132
Majed Al-Bishi – 216423
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History of Fiber Optic Technology People have used light to transmit info. for hundreds of
years The invention of the laser prompted researchers to study
the potential of fiber optics send a much larger amount of data than telephone first experiment letting the laser beam transmit freely in air & through different types of waveguides very large losses in the optical fibers prevented coaxial
cables from being replaced Decrease in the amount of light reaching the end of
the fiber
Cont: History of Fiber Optic Technology
Early fibers had losses around 1,000 dB/km In 1969, several scientists concluded that impurities in the
fiber material caused the signal loss Researchers believed it was possible to reduce the
losses By removing the impurities researchersobserve the improvement In 1970,(corning glass works)* made a multimode fiber with
losses under 20 dB/km. in 1972, the company made a high silica-core multimode
optical fiber with 4dB/km. Nowadays, multimode fibers can have losses as low as 0.5
dB/km at wavelengths around 1300 nm
*company
Introduction Optical fiber has a number of advantages over the copper
wire since it is made glass or plastic
light has a much higher frequency than any radio signal we can generate, fiber has a wider bandwidth To carry more information at one time
Transmitters transmitters include an LED(Light-emitting diodes) or
laser diode
LED produce incoherent light
have relatively large emitting areas and as a result are not as good light source
they are widely used for short distances because they are much more economical
Cont: Transmitters Laser diode produce coherent light used for applications that require the
transmission of signals over long distances Important performance specifications
data rate transmitter rise time wavelength spectral width maximum optical output power
Receivers Receivers are instruments that convert light
into electrical signals.component of an optical receiver is a
photo detector that converts light into electricity
use three types of photodiodespositive-negative (PN) junctionspositive-intrinsic-negative (PIN) photodiodesavalanche photodiodes (APD)
Optical FiberFiber is the medium to guide the light form
the transmitter to the receiver. There are two types:
Multimode FiberSingle-Mode Fiber
Multimode FiberIn multimode fibers more than one light
transmitted at a time.Fiber diameter ranges from 50-to-100
micron.
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Multimode FiberMultimode Fiber is divided into two types:
Multimode Step-index FiberMultimode Graded-index Fiber
Multimode Step-index FiberLights are sent at angles lower than the
critical angle or straightAny light angle exceed the critical angle will
cause it to penetrate through cladding.Obviously light with lower angle will reach
the end faster than others.
Multimode Step-index FiberThe difference in signals receiving time
result in unstable wave light at the receiver.To avoid this problem there should be
spacing between the light pulses but this will limit the bandwidth.
Used for very short distance
Multimode Graded-index FiberIn this mode reduce the problem with
Multimode Step-Index.All the beams reaching the receiver almost at
the same time.This can be done by slowing down the ones
with shorter distance.This is done in fiber implementation by
increasing its refractive index at the center and gradually decreases it toward the edges
Single-Mode FiberOnly one light is transmitted in the fiber.Diameter ranges from 8.3 to 10 microns.It has Higher transmission rate.it can be used for longer distance.
Fiber CablesAdvantages of Cabling fiber:
Ease of HandlingProtectionCrush ResistanceDegradation
Types of Fiber Cables:Loose Tube CableTightly Buffered CableRibbon Cables
Wave Division Multiplexing (WDM)
it is a way to send multiple optical signals from deferent source at the same time on one optical fiber.
Used with single mode fiberHow it works:
At the sender the data stream from each Source is assigned an optical wavelength.
The multiplexer modulates each data stream from each Source.
The resulted optical signal generated for each source data stream is placed on its assigned wavelength.
Wave Division Multiplexing (WDM)
The resulted signals are simultaneously sent through the fiber.
At the receiver the signal is separated into the original signals according to their different wavelengths by using prisms.
These signals are further demodulated.Then, The resulting separated data streams
are provided to the respective Users.
Some ApplicationLong telecommunication systems on land and
at sea to carry many simultaneous telephone calls (or other signals) over long distances.
Links among computers and high resolution video-terminals.
Local area Networks operating at high speeds.
Connections between the telephone N/W and antennas for mobile telephone service.
Interoffice trunks that carry many telephone conversations simultaneously between local and regional switching facilities.
Thank you
Any Question please
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