August 1962 Electronics World
Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
Electronics World, published May 1959
- December 1971. All copyrights hereby acknowledged.
In 1962 when this Bell Telephone
Laboratories infomercial appeared in Electronics World magazine, scientists
were in the early stages of developing communications via light signals. Most lasers
(light amplification by stimulated emission of radiation) were still of the ruby
type mentioned here. In fact, it was only two years previous in 1960 that Theodore
Maiman created the world's first "optical maser" using a ruby.
The term "maser" ("microwave amplification
by stimulated emission of radiation") seems to be a bit of a misnomer, but under
the proper conditions it could operate in the visual or infrared regions of the
electromagnetic spectrum. "Could coherent light, for example, be sent through protecting
pipes to provide high-capacity communication channels between cities?," the copy
asks. We now know the answer to that question as optic fiber now spans the globe,
literally. This is one of the main reasons I like to post these items from vintage
magazines: to remind - or maybe to inform for the first time - people of who it
was that developed all the knowledge taken for granted by such a large fraction
of the population. Of course many of the "cancel culture" Bozos who want to punish
companies and individuals for having existed at a time when cultural and societal
standards were different have no interest in according due credit to those who came
before them regardless of their accomplishments.
Bell Telephone Laboratories Ad
Exploring the possibilities in Coherent
At Bell Laboratories, Donald F. Nelson studies a beam of coherent red light produced
by a continuously operating ruby optical maser. The heart of the device is a uniquely
shaped ruby crystal immersed in liquid nitrogen in the tubular glass Dewar extending
from upper left to center. Light from the mercury arc lamp (lower center) is reflected
by round mirror at left to mirror at right and then is focused on the ruby crystal
to produce maser action. Coherent light emerging from end of Dewar is picked up
by a detector.
Is it feasible to take advantage of the enormous bandwidth available at optical
frequencies? Could coherent light, for example, be sent through protecting pipes
to provide high-capacity communication channels between cities?
To study such possibilities it is, first of all, necessary to have a source of
continuous coherent radiation at optical frequencies. Such a source was first produced
when Bell Laboratories scientists developed the gaseous optical maser.
Recently, our scientists demonstrated the generation of continuous coherent light
by solid materials. Using a crystal of neodymium-doped calcium tungstate, a material
developed at Bell Laboratories, continuous optical maser action was obtained in
the near infrared. It has also been attained with visible light, using a new optical
"pumping" arrangement to excite a ruby crystal. (See illustration above.)
Multichannel light highways for communications are still far from realization.
But with continuous sources of coherent light available, it becomes possible to
explore the problems of modulating, transmitting, detecting, amplifying and, in
general, controlling light for possible communications applications.
Bell Telephone Laboratories
World center of communications research and development
Posted June 14, 2021