The Review begins with brief highlights of the history of fiber optics, followed by a discussion of the attributes of shortwave and longwave transmission. This leads to an investigation of various fiber types, short-haul considerations, and then single-mode aspects. Specialty fiber is briefly covered, followed by a survey of several research trends today that will lead to new systems capabilities in the future. No references are given, since hundreds would be necessary to make the list even partially complete.

Today, fiberoptic cables are being installed routinely in a wide variety of environments with the expectation that they will operate for many years. Worldwide, there is a very large number of successful cable installations, and the transmission performances of some of them have been monitored closely for up to seven years. These installations are possible because a great deal of effort has been given to developing cable designs tailored to fiberoptics.

Measurement methods used in normal installation or maintenance activities cn optical fiber communication systems are reviewed. Measurements discussed include fiber cable continuity, attenuation, bandwidth/dispersibn, optical time domain reflectometry, power penalty, bit error rate, optical margin, and eye degradation. Test methods described are based upon current Electronic Industries Association (EIA) draft standards. Advantages and disadvantages of various testing techniques used within laboratory and field environments are addressed. Indepth details and special considerations are presented on the topics of fiber cable attenuation, bandwidth, and optical time domain reflectometry for singlemode and multimode fielded systems. Problems with field environments are highlighted and field tests are related to EIA standard factory tests.

The methods of splicing optical fibers are considered in two broad categories: (1) fusion splices; and (2) mechanical splices. Various types of fusion splicing equipment and mechanical splice alignment means are described, with characheristics and cost compared. The information in this overview of fiber optic splices provides a basis for identifying which splicing methods to use for particular applications.

Connector and fiber manufacturers have succeeded, to a remarkable degree, in solving their common problem of transferring optical energy from one optical waveguide to another in a reasonably efficient manner. Fiber optic cables and connectors have been on the market for over 10 years during which time the loss in connecting two fibers has gone from greater than 5 dB to less than 1 dB. Concurrently, fiber manufacturers have reduced their core/ cladding diameter variations from +6 microns to 2 microns in 50/125 micron core/clad diameter fibers. Improvements in core/clad concentricity, ovality, and numerical aperture variations have also been made. For a time, a finger pointing exercise went on between connector and fiber manufacturers as to who was responsible for the greatest part of con-nector losses (the separation of losses into intrinsic and extrinsic parts). Both parties had to work together to improve their own product as well as the interface, resulting in better products for the users.

This tutorial review of fiber-optic branching devices covers example uses of branching devices, device types, device-performance characteristics, examples of current technology, and system-design methodology. The discussion is limited to passive single- and multimode devices fabricated from optical fibers or graded-index components. Integrated-optic, wavelength-division-multiplexing, and polarization-selective devices are not specifically addressed.

This paper presents a survey of technical issues concerning the specification and use of optoelectronic devices and components in fiber optic communications. It is intended to bring together current understanding of the performance of fiber optic systems using relatively straightforward models for device and transmission characteristics. Where possible, formulas and graphical presentations of the phenomona are presented. Representative observations of significant effects are offered as guides to the magnitude and impact of the phenomena.

An interest in optical communications was created in 1960 with the discovery of the laser1. The initial activity concentrated on experiments using atmospheric optical channels, since early optical fibers had extremely large losses of more than 1000 dB/km which made them appear impractical. This changed in 1966 when it was speculated that these high losses resulted from impurities in the fiber material, and that losses could be reduced significantly2 . Simple calculations showed that in order for a fiber optic transmission link to have two-km repeater spacings, which was comparable to existing coaxial systems, fiber attenuation on the order of 20 dB/km would be required. This was realized in 1970, and a whole new era of optical fiber communications was thus launched3-4. In this paper, we will examine some of the general features of various digital systems, and will discuss the strengths and limitations of the transmission links that have emerged to date.

The fiber optic technology advances of long wavelength and single mode fibers significantly increases the capabilities of fiber optic analog transmission. This paper will review fiber optic analog transmission performance capabilities, limitations, and applications areas.

The use of the fiber optic transmission medium in local area networks is explored. A taxonomy of LANs is presented, and it is shown that fiber may be considered as a universal medium for the different varieties of possible systems. The trends for future fiber systems are examined, and it is demonstrated that fiber may be used to extend the capabilities of traditional networks and also make possible new and different architectures designed to exploit the bandwidth of fiber.

A review of Wavelength Division Multiplexing Technology will be presented.