The optical fibers are the source of a technological revolution in telecommunications, because they are capable of navigating light over thousands of kilometers.The main objective of our project is to show how communications using fiber optics can meet the explosive growth of E-traffic expected in the coming years.
Brief History:
"The knowledge Science is not absolute ,
but socially , culturally , technologically and historically marked ,
therefore provisional." [Steven Rose]
1810: Discovery of illuminated fountains by Tyndall.
Light rays enter the water along the jet axis, leaving them trapped.
1880: Invention of camera phone by Alexander Graham Bell.
The voice is transmitted over a few tons of meters of air by a light ray modulated at a rate of sound waves.
1887: First fiber glass by Boyes.
The principle of illuminated fountains is applied to glass fibers of about fifty meters.
1960: First laser, and thus generation of coherent light, monochromatic and stable.
1966: First fiber-optic silica by Kao and Hockman.
Nonetheless, absorption lost in optical fibers was such that the signal disappeared after a few centimeters.
1972: Manufacture of first optical fibers, or at least the first fibers sufficiently transparent to be used in telecommunications.
Principle of the fiber:
"Words and how we use it,
may provide some insight on the principles of our ideas. "
[Etienne de Condillac]
Structure:
"There is no structure better but different structures that are
the best in different conditions."
[J. Woodward]
The laws of Snell are both the source properties of the optical fiber.The latter is composed of two environments: a heart, in which light is confined, and a sheath, whose refractive index is slightly lower than the heart. If the angle at which the light beam attack the sheath is greater than or equal to the critical angle defined by the two circles and their respective refractive indices, it will reflect multiple times in the fiber, due to the total reflection that takes place inside.
Main characteristics:
"If there is one characteristic universal in this life,it's good that all ends by pass ."
[Doric Germain]
Attenuation:
Loss of silica optical fibers: The main advantage of optical fiber attenuation is extremely low. The mitigation will vary depending on the wavelength. It decreases exponentially with an absorption peak around 1385 nm, due to the presence of OH radicals in silica, and a minimum attenuation around 1550 nm.That's why we use this wavelength in infrared optical communications channels. However, over long distances, the signal reamplifies regularly.
Chromatic dispersion: When one sends a light signal, there are many wavelengths present, either because the source is extended, or because the source is actually peak centered on a wavelength. Chromatic dispersion shows characteristic enlargement of the signal related to the width of its spectral . Hence, if two different wavelengths do not propagate at the same speed, the output signal will be distorted.
Modal dispersion: Mode dispersion characteristic of signal shows disinclination due to the fact that the fiber is not perfectly circular.
Tags: optical fibers, technological revolution, telecommunications, fiber optics, Kao and Hockman, Chromatic dispersion, silica optical fibers
[...] There are also infrastructure like FTTCab (FTT Cabinet, where the optical fiber ends at the splitter) and FTTCurb (Curb meaning sidewalk, there is an average of 300 meters from the client, which allows high flow rates). IP (Internet Protocol) This characterizes the abbreviation name, unique on a given network, which identify a computer connected to that network. An IP address consists of 4 numbers and 3 points (example: Currently we use IPv4 numbers), especially for managing the internet, but the relatively small number of possibilities (256 x 256 x 256 x 256) that the system IPv6 is starting are to interest and attract the developers. [...]
[...] Comparison with other guides " All things are good or bad by comparison [Edgar Allan Poe] Features Optical Fibre Copper Wire Materials Dielectric Driver (That is to say insulator) Transmission medium Photons Electrons signal Sensitivity to electromagnetic Null Great * interfaces receivers Wide bandwidth Great Limited by corrosion) Flexible network and Network soon to be Adaptability adapts easily to new obsolete technologies Weight Very light Largest * However, in the case of a coaxial cable (center conductor surrounded by a dielectric itself surrounded by a conductive shield), the Faraday cage formed by the sheath boundary, or electromagnetic interference stops. [...]
[...] Connection There are currently two main ways of connecting two optical fibers together: - First being mechanical coupling, carried out with 2 connectors and a piece of precision (the connectors are the most popular ST and SC connectors), for which the weakening caused by a connection point is less than or equal to 0.7 dB for 1300 and 1550 nm - Second being the coupling fusion, performed by an automatic splicer, which will also ensure alignment, the tensile test after welding, and measuring the attenuation at 1310 nm and 1550 (on average between 0.03 and 0.1 dB up to 0.15 dB) . [...]
[...] Law of refraction: the case of optical surfaces-planes Statement: The refracted ray lies in the plane of incidence and the angle checks: No sin = n 2. sin 2). The interface between two media is called the interface. The incident ray is said to be refracted or transmitted after crossing the surface, that separates two media. From the first law, we find the point of incidence the plane of incidence and the angle of incidence, which is named as i The oriented angle defined by the normal to the refracted ray is the angle of refraction. [...]
[...] In the DSL family, there are ADSL and SDSL's, whose initials correspond to Symmetrical and Asymmetrical providers., ADSL provides a lower uploaded version than a downloaded version , which is more appropriate to a user. The Web, where SDSL bandwidths are equal, allow the creation of a web server. Other DSL standards exist, such as ADSL2 + (DSL second generation has doubled its bandwidth), or the RADSL (Rate Adaptive DSL), whose flow adapts to the physical characteristics of the channel (modems using this technology do a test on the line at the beginning of communication and adapt the speed to match the bandwidth). [...]
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