City of Light: The Story of Fiber Optics

178 CITY OF LIGHT
modest increase in transmission speed at those wavelengths. The toughest
choice was between gallium arsenide lasers and LEDs; lasers were brighter,
but in 1975 they didn’t last long. Bell hedged its bets and worked on both.
The consensus reflected a widespread belief that the technology was near
a plateau. The best laboratory fibers were approaching the fundamental
limit on transparency at 850 nanometers, two decibels per kilometer. 8 Developers
added in other losses expected in production fibers, connectors, and
splices and figured signals couldn’t go much beyond 10 kilometers (6 miles)
without a repeater. Graded-index fibers could easily carry tens of millions of
bits per second over that distance, and perhaps a few hundred million. After
15 years of development, gallium arsenide lasers were approaching desirable
lifetimes.
A few labs pushed a bit further. The Post Office tested gallium arsenide
lasers and graded-index fibers to transmit similar distances at the European
standard speed of 140 million bits per second. 9 A team at Fujitsu sent 400
million bits per second through 4 kilometers (2.5 miles) of graded-index fiber
and held out hope for even faster transmission. 10 However, the industry generally
followed the Bell Labs consensus.
The little village of fiber-optic developers had become a fast-growing town.
When Charles Kao returned from Hong Kong in 1974, he found himself an
elder statesman in his early forties. He was honored for recognizing fiber’s
potential, although he had underestimated the transparency of silica and the
industry had turned away from his suggestion of single-mode fiber. ITT gave
him a high profile, sending him to Roanoke, Virginia, to launch a new American
fiber-optics group.
A few others held to the original vision of single-mode fibers. Dick Dyott
felt alone, ‘‘bleating in the wilderness’’ about their virtues before he left
the Post Office in 1975. 11 Developers of submarine cables were interested
because they had to stretch transmission speeds and distances as far as
possible, but they were not ready to invest much. F. F. Roberts and Stew Miller
thought single-mode fibers were long-term possibilities but gave them low
priority for use on land. The biggest single-mode project was a Navy effort
to develop acoustic sensors to track the movement of Soviet nuclear submarines.
A Fiber-Optic Gold Rush
At the end of May 1976, Bell Labs reported that the Atlanta trial had worked
better than expected. Deep collective sighs of relief were breathed. Much more
detailed analysis remained, 12 but the basic message was loud and clear: Fiber
works. That was more than sufficient to launch a fiber-optic gold rush.
Hot new technologies lure would-be entrepreneurs like rumors of a gold
strike draw miners. Corning fueled the fires when it attacked corporate financial
problems by companywide layoffs that hit the fiber group. Corning’s fiber