fiber obtik

Light wave communication was first considered more than 100 years ago. The implementation of optical communication using light waveguides was restricted to very short distance prior to 1970. Corning Glass Company achieved a breakthrough in 1970 by producing a fused silica (SiO2) fiber with a loss approximately 20 dB/km. The development of semiconductor light source also started to mature at about that time, allowing the feasibility of transmission over a few kilometers to be demonstrated. Since 1970, the rate of technological progress has been phenomenal, and optical fibers are now used in transoceanic service. Besides the long-distance routes, fibers are used in the inter-CO (inter exchange) routes, and the subscriber loop in the final link in what will eventually be the global interconnection chain. Optical fibers are associated with high-capacity communications. A lot of attention is presently being given to optical fibers to provide a very extensive broadband ISDN. Fiber optics is defined as that branch of optics that deals with the transmission of light through ultrapure fibers of glass, plastic, or some other form of transparent media. From a decorative standpoint, most of us are familiar with the fiber optic lamp, which uses bundles of thin optical fibers illuminated from the base end of the lamp by a light source. The light source is made to vary in color, which can be seen at the opposite ends of the fiber as a tree of illuminating points radiating various colors of the transmitted light. Although the lamp is used for decorative purposes only, it serves as an excellent model of how light can be transmitted through the fiber. 2.1 Light Light is a kind of electromagnetic radiation. The basic characteristic of electromagnetic radiation is its frequency or wavelength. Light frequencies fall between microwaves and x-rays, as shown in Figure 2.1.