AUTOMATION TRENDS USING FIBER OPTIC LINKS

AUTOMATION TRENDS USING FIBER OPTIC LINKS

ABSTRACT

An optical fiber (or fiber in British English) is a transparent thin fiber for transmitting light. Fiber optics is the branch of science and engineering concerned with optical fibers. ,
The optical fiber can be used as a medium for telecommunication and networking because it is flexible and can be bundled as cables. Although fibers can be made out of either plastic or glass, the fibers used in long-distance telecommunications applications
are always glass, because of the lower optical absorption of glass. The light transmitted through the fiber is confined due to total internal reflection within the material. This is an important property that eliminates signal crosstalk between fibers within the cable and allows the routing of the cable with twists and turns. In telecommunications applications, the light used is typically infrared light, at wavelengths near to the minimum absorption wavelength of the fiber in use.
Fibers are generally used in pairs, with one fiber of the pair carrying a signal in each direction.
Because of the remarkably low loss and excellent linearity and dispersion behavior of single-mode optical fiber, data rates of up to 40 Gbit/s are possible in real-world use on a single wavelength. Wavelength division multiplexing can then be used to allow many wavelengths to be used at once on a single fiber, allowing a single fiber to bear an aggregate bandwidth measured in terabits per second.
Modern fiber cables can contain up to a thousand fibers in a single cable, so the performance of optical networks easily accommodate even today’s demands for bandwidth on a point-to-point basis. However, unused point-to-point potential bandwidth does not translate to operating profits, and it is estimated that no more than 1% of the optical fiber buried in recent years is actually ‘lit’. Recent advances in fiber technology have reduced losses so far that no amplification of the optical signal is needed over distances of hundreds of kilometers.
This has greatly reduced the cost of optical networking, particularly over undersea spans where the cost reliability of amplifiers is one of the key factors determining the performance of the whole cable system. Longer-range systems still have to use optical amplifiers