Page 23 - Optical Switching And Networking Handbook

8 Chapter 1

History of Optical and Fiber in

Telecommunications

Let’s take a trip down memory lane and discuss the use of optical
communications in the telecommunications industry from its incep-
tion to the development of the various types and modes of fiberoptic
systems. The beginning of optical communications is rather inter-
esting. It has always been a belief that if you want to know where
things are going, you have to understand where they have been. A
little history will help.
Optical communications systems date back to the “optical tele-
graph” invented by French engineer Claude Chappe in the 1790s. He
used a series of semaphores mounted on towers, with human opera-
tors relaying messages from one tower to the next. Of course, in
order for this to work, the people had to be close enough together to
visually see the other messenger’s motions. This was not a great ser-
vice for evening transmission and had some problems with weather
conditions (for example, fog, heavy rain, heavy snow, and so on). The
system depended on a line-of-sight operation; hence, the towers
needed elevation to extend the coverage (albeit, a limited distance
between repeaters) and close proximity.
However, the optical telegraph did perform better than hand-
carried messages. Alas, by the mid-nineteenth century the system
was replaced by the electric telegraph, leaving a scattering of
“telegraph hills” as its legacy.The use of electrical transmissions was
better suited for communications over distances.
In 1880, Alexander Graham Bell patented an optical telephone
system, called the photophone. His earlier invention, the telephone,
was far more practical and widespread. Bell dreamed of sending sig-
nals through the air. Unfortunately, the atmosphere did not carry
transmitted light as reliably as wires carried electricity. Light was
used for a few special applications, such as signaling between ships,
but otherwise, optical communications did not achieve the expected
results.
Later, a new technology began to take root that ultimately would
solve the problem of optical transmission. It took a long time before
it was finally adapted and accepted for voice and data communica-