National Geographic : 1979 Oct
Clearing the lines for communications IN THE SECOND CENTURY of the telephone, cables with S144 opticalfibers, like the one developedby Bell Laboratories (below), will help ease the telephone trafficjam. More than a hundred systems in countriessuch as Britain,Canada,and the United States now use fiber cables. Most fibers at present are made in lengths of ten kilometers (six miles). Field use requires splicing longer lengths (se quence, below left). Ends cut with a diamond stylus are aligned, thenfused by an electric arc. A laserbeam sent through2.2 kilometers offiber wound on a drum measures light loss (left). In actual use, messages are pulsed on a beam of infraredlight invisible to the eye. The idea of using light in telephone communicationsis not new. In 1880 Alexander Graham Bell invented a phone that used sunlightin placeofwires. "I have hearda rayof sun laugh and cough and sing," he wrote.