City of Light: The Story of Fiber Optics

A t
7
A Vision of the Future
Communicating with Light
(1880–1960)
In the region that includes the visual spectrum [and] the
near infra-red, there is about nine hundred million megahertz
of bandwidth waiting to be used. This is enough for
seven thousand million speech channels of present-day
standards, using a digital method such as PCM [pulse
code modulation]. ...It would be enough too for the
PCM transmission of one and a half million individually
used TV channels, with color and stereo-type 3-D features,
of standards that the future will require. If the traffic loaded
it at all fully, even one percent of this bandwidth per conductor
could easily make all lower frequency methods that
are now foreseeable as obsolete eventually as the stagecoach.
—Alec Harley Reeves, 1969 1
first glance, communicating through optical fibers seems simpler than
imaging. You only need a single fiber to carry a light signal between two
points. Yet anyone who looked closely at the idea in the late 1950s saw a
much different picture.
The first and most obvious problem was transparency. Larry Curtiss, Will
Hicks, and the engineers who worked with them had made tremendous progress,
but their clearest bundles carried images only a few yards or meters.
Six feet of fiber is more than enough to look into the stomach, but it may not
76