ATTENUATION CHARACTERISTICS OF TRANSMITTED SIGNALS USING DIFFERENT TYPES OF OPTICAL CABLES

Abstract

The first theoretical study of wave propagation in dielectric waveguides appeared in 1910, little interest develQped until the advent of microwaves in the late 1940's and of lasers in the early 1960's. These early fundamental studies were concerned with wave properties oflow-order guided modes, but did not include considerations of signal attenuation and pulse distortion aspects important to the transmission of information.

After some theoretical work about the multimode nature of the propagation in optical fibers, the first proposal of employing this transmission medium in long-distance communications was made in 1966, under the assumption that silica-based glasses have an

intrinsic loss, due to absorption and scattering, at some operating wavelengths, on the order of 20 dB/km. In 1974 the value of 2 dB/km was reached at 0.85 J.lm, 0.47 dB/km was obtained at 1.3 J.lm in 1976, and 0.2 dB/km was finally achieved at 1.55 J.lm in 1979.

In this thesis, some of the important optical-fiber structures, parameters, and properties associated with signal transmission were considered. The discussion covers multimode waveguides and includes their basic structural features and physical parameters, materials properties, various loss mechanisms, and loss spectra.

Thus, this work describes state of the art measurement techniques for the characterization of fiber loss.