Home >>
Communications History >>
Current Technology >>
Optical Cable
In 1880, an American inventor from Concord, Massachusetts named
William Wheeling patented a concept he called "piping light." He
believed that, in the same way as water could be distributed through
a house via plumbing, light too could be transmitted through a
series of pipes.
In this unusual twist on the optical telegraph, Wheeling felt
that, theoretically, light could be used to convey information to a
number of places at once. Unfortunately, his invention proved
ineffective and was quickly forgotten.
Instead, Alexander Graham Bell’s photophone came closest to
predicting both early fibre optic technology and later advances in
the free-space optics that allow data transmission through infrared
light beams.
Perhaps surprisingly, this technology did not progress much past
Bell’s work until the 1950s, when Brian O’Brien, a researcher at the
American Optical Company, developed the first image-transmitting
fibres. This early development was only marginally effective at
transmitting imagery, because the light flashed through it quickly
degraded.
Meanwhile, Indian-born Narinder Kapany, working out of England,
created the fibrescope out of simple glass tubing. Kapany’s
design—wherein light was transmitted through a glass core and
protected from degradation by an outer coat of different glass
called "cladding"—worked to keep a pure signal within the optical
cable.
An outer coating was then added to protect the glass cable from
breakage. Information was sent from a transmitter through the cable,
via light, to a receiver—in this case, a photodiode—that could
translate that signal back into electrical current.
Because this new design was more efficient than the older model,
it was soon put to commercial use.
In 1956, Kapany was the first to use the term "fibre optics" to
describe this technology.
Gordon Gould, a graduate student at Columbia University in New
York City, worked with laser technology, and understood the small
and intense beam of light he could generate would be most effective
for travelling through fibre optics. The Light Emitting Diode (LED),
a device capable of translating electrical current directly into
light, could also serve the same purpose.
Light is capable of sending much more information than are radio
frequencies, so the communications industry took immediate notice of
these new developments. The key was to minimize further the massive
light loss that occurred as the beam travelled through the core of
optical cable.
The problem was quickly traced to impurities within the glass
itself, and 1970 saw the development of glass pure enough to create
effective fibre optics.
The US military was among the first groups to make regular use of
this technology, through the late 1970s, taking advantage of a new
generation that further diminished the amount of light lost.
Broadcasters soon followed suit, albeit more slowly, and the
telephone companies became involved later still.
Because optical cables were more efficient at sending large loads
of data, fibre optics allowed smaller telephone companies to compete
more readily with larger ones. The technology spread slowly,
however, especially in places accustomed to harsh weather. Various
interests within the province of Alberta have worked to increase the
availability of this efficient technology.
Alberta SuperNet provides an example of how fibre optics can be
used to provide quick connections for large numbers of people.
Copyright © 2004
Heritage Community Foundation and
Telephone Historical Centre All Rights Reserved
|