City of Light: The Story of Fiber Optics

270 CITY OF LIGHT
abandon thin-film waveguide in favor of singlemode
clad optical fiber.
February 1965: Stewart Miller of Bell Labs applies for patent on
graded-index waveguides for light and millimeter
waves.
Autumn 1965: Kao concludes that the fundamental limit on glass
transparency is below 20 decibels per kilometer,
which would be practical for communications.
Hockham calculates that clad fibers should not radiate
much light. They prepare a paper proposing
fiber-optic communications.
January 1966: Kao tells Institution of Electrical Engineers in London
that glass fibers could be made with loss below 20
decibels per kilometer for communications.
Early 1966: F. F. Roberts starts fiber-optic communications research
at British Post Office Research Laboratories.
July 1966: Kao and Hockham publish paper outlining their proposal
in Proceedings of the Institution of Electrical
Engineers.
July 1966: John Galt at Bell Labs asks Mort Panish and Izuo
Hayashi to figure out why diode lasers have high
thresholds at room temperature.
September 1966: Alain Werts, a young engineer at CSF in France,
publishes proposal similar to Kao’s in Frenchlanguage
journal L’Onde Electronique, but CSF does
nothing further for lack of funding.
1966: Roberts tells William Shaver, a visitor from the Corning
Glass Works, about interest in fiber communications.
This leads Robert Maurer to start a small
research project on fused-silica fibers.
1966: Kao travels to America early in year but fails to interest
Bell Labs. He later finds more interest in Japan.
Early 1967: British Post Office allocates an extra £12 million to
research; some goes to fiber optics.
Early 1967: Shojiro Kawakami of Tohoku University in Japan
proposes graded-index optical fibers.
Summer 1967: Corning summer intern Cliff Fonstad makes fibers
with Frank Zimar. Loss is high, but Maurer decides
to continue the research using titania-doped cores
and pure-silica cladding.
October 1967: Clarence Hansell dies at 68.
Late 1967: Robert Maurer recruits Peter Schultz from Corning’s
glass chemistry department to help make pure
glasses.