City of Light: The Story of Fiber Optics
City of Light: The Story of Fiber Optics
City of Light: The Story of Fiber Optics
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A VISION OF THE FUTURE 87<br />
caused by uneven settling <strong>of</strong> the soil. Like a high-speed railroad line or interstate<br />
highway, it required broad, sweeping curves. That would make installation<br />
costly, but AT&T could accept that. Waveguides promised tremendous<br />
capacity, and they were to run mostly between cities, not within them.<br />
After two years <strong>of</strong> tests, Bell Labs settled on a design for 50.8 millimeter<br />
(2-inch) waveguides each carrying 80,000 conversations at frequencies between<br />
35 and 75 gigahertz. <strong>The</strong> signals would be digitized and transmitted<br />
by pulse-code modulation, as Reeves had proposed 21 years earlier. 28 <strong>The</strong><br />
overall data rate would be a then-staggering 160 million bits per second.<br />
Meanwhile, Bell Labs was also pursuing another long-distance alternative,<br />
the communications satellite. Arthur C. Clarke, a British engineer and writer,<br />
had come up with the idea during World War II as an alternative to radio<br />
relays and coaxial cables. Both <strong>of</strong> those systems required chains <strong>of</strong> repeaters<br />
to span long distances. However, Clarke realized that a satellite with an orbit<br />
lasting exactly one day would stay continually over the same place on the<br />
equator, so a transmitter on board could relay signals between any two points<br />
on its side <strong>of</strong> the Earth. 29 John R. Pierce, a top Bell Labs communications<br />
engineer who also worked on millimeter waveguides, picked up on the idea<br />
in the 1950s and pushed it as the Space Age emerged. Like Clarke, Pierce<br />
had published science-fiction stories, but Pierce was primarily an engineer<br />
and saw the practical potential <strong>of</strong> satellite communications, which became<br />
the first important civilian use <strong>of</strong> space technology. 30<br />
Standard Telecommunication Labs concentrated on millimeter waveguides,<br />
but Reeves was not impressed by early trials. Congested Britain didn’t<br />
have room to bury pipes with sweeping curves, small irregularities caused<br />
disturbing losses, and no technology was available for the amplifiers needed<br />
to compensate for the inevitable losses. He didn’t like the costly, brute-force<br />
approach, so he considered a bolder alternative—moving all the way to light.<br />
<strong>The</strong> gap between microwave and optical frequencies is a factor <strong>of</strong> 100,000.<br />
That seemed overwhelming to most, but Reeves realized the difference was<br />
the same as the gap from long waves to microwaves he had seen crossed in<br />
his 35 years <strong>of</strong> engineering. He had a hunch light would work better, and<br />
he was a man who listened to his hunches because they <strong>of</strong>ten were right. 31<br />
Reeves hoped that mental telepathy might be the ultimate communications<br />
technology, 32 but he didn’t know how to tame that, so light would have to<br />
suffice.<br />
A Pioneering Effort<br />
Reeves knew little about light until STL landed a military contract in the field<br />
in 1952. <strong>The</strong> contract required a working knowledge <strong>of</strong> optics, so he hired<br />
Murray Ramsay, a young physics graduate from University College London,<br />
who had been a scout in Reeves’s troop before the war. <strong>The</strong> ever-curious<br />
Reeves pumped the young Ramsay for information and pondered the prospects<br />
for optical communications in his smoke-filled <strong>of</strong>fice at STL. He tested