City of Light: The Story of Fiber Optics

8
The Laser Stimulates the
Emission of New Ideas
(1960–1969)
Usable communication channels in the electromagnetic
spectrum may be extended by the development of an experimental
optical-frequency amplifier announced by
Hughes Aircraft a few days ago.
—Electronics magazine, July 22, 1960 1
E li Snitzer was not the only person distracted by the laser. Its invention was
big news in 1960. Military planners and science-fiction fans saw it as the
ray gun of their dreams, but engineers and physicists recognized it as the first
optical oscillator, and the first practical source of coherent light. 2 They immediately
recognized its development as a milestone on the road to optical
communications, although it was far from clear where the road was going.
Radio engineers use oscillators to generate the pure carrier frequencies that
are modulated to transmit radio signals. Radio oscillators drive antennas so
they radiate coherent radio waves, which share the same frequency and stay
in phase with one another, like a troop of identical soldiers marching in step
on parade. That frequency must be pure so that radio receivers can essentially
cancel it out to recover the transmitted signal.
When Reeves started looking at optical communications, there were no
practical sources of coherent light. Light bulbs, stars, and virtually all other
common sources emit light spanning much of the spectrum that spreads unsynchronized
across the universe like a crowd leaving a baseball stadium after
the game is over. You can switch a light bulb off and on, but it doesn’t
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