| One of the most important
technological developments during the 1980s has been the emergence of optical
fiber communication as a major international industry. One indication of the{{U}}
(51) {{/U}}of this development is the total{{U}} (52) {{/U}}of
installed fiber, which was estimated to be 3.2 million kilometers in the U.S.
alone by the end of 1987. Over 90% of this fiber was placed.{{U}} (53)
{{/U}}during the time period of 1982—1987. Long-haul trunk
installations(长途干线设施) have dominated,{{U}} (54) {{/U}}for about 95% of
the fiber in the U.S. In the early 1950s the researchers who produced the first clad glass optical fibers were not{{U}} (55) {{/U}}of using them. for communications.{{U}} (56) {{/U}} , fiber optics was already a well-established commercial technology when the famous paper by Kao and Hockham,{{U}} (57) {{/U}}the use of low-loss optical fibers for communication, appeared in 1966. The first low-loss silica fiber was described in a publication which appeared in October of 1970. The date of this publication is sometimes{{U}} (58) {{/U}} as the beginning of the era of fiber communication. Although this development did receive{{U}} (59) {{/U}}attention in the research community at- the time, it was far from inevitable that a major industry would evolve. The technological barriers appeared{{U}} (60) {{/U}}because there were serious doubts as to{{U}} (61) {{/U}}these fiber components could ever be produced economically enough, but the market potential was very significant.{{U}} (62) {{/U}}, research and development activity expanded rapidly, and a number of important issues were{{U}} (63) {{/U}}during the early 1970s. During the middle and late 1970s, the rate of progress towards marketable products accelerated as the emphasis {{U}}(64) {{/U}}from research to engineering. Fibers with losses approaching the Payleigh limit of 2 dB/km at a wavelength of 0.8um were produced. By 1980 improvement in component performance, cost, and reliability led to major commitments{{U}} (65) {{/U}}the part of telephone companies. |