Advances in Communication through Light Fibers

Abstract

Publisher Summary This chapter focuses on the advances in communication through light fibers. Recent breakthrough in the purification of glass has made it possible to manufacture very low-loss optical fibers. The fibers provide almost all the attractive features of an ideal optical transmission line, such as, low cost, small size, lightweight, flexible, larger bandwidth, high tensile strength, no short circuiting issues, resistant to nuclear radiation, and heat resistance. These optical fibers are used as the communication media for transmitting optical signals. The bandwidth of a single-mode fiber is limited by the dispersion of the normal mode and by the material dispersion effects. One of the unique characteristics of a dielectric fiber waveguide is that below a certain frequency called the cut-off frequency of a particular mode, that mode simply no longer exists. A fiber of a given cross section will support a finite number of guided modes and a continuous spectrum of radiation modes. Any irregularity in the fiber because of diameter variation, bending, interface irregularities, or the presence of scattering centers will produce coupling of the energy of one mode to the others. Mode coupling within an optical fiber may produce the desirable effect of reducing the delay distortion that result from uncoupled multimode operation or may produce the undesirable effect of signal contamination.