City of Light: The Story of Fiber Optics

166 CITY OF LIGHT
proposed, Bell concentrated on interoffice transmission. Initially it was a quiet
program, virtually invisible to the outside world. The general press ignored
it, and even the technical press took time to catch on. 32 In early 1971, John
Kessler at Electronics magazine picked up rumblings of the fiber-optic revolution,
but only after a few months did he realize its importance and write a
cover article. 33 Even advocates were cautious. ‘‘Corning has several fibers
about 200 meters long which exhibit losses of 20 dB’’ per kilometer, said
Chuck Lucy, ‘‘but this is a long way from a system.’’ 34 Technology trends
were unclear; Corning and others were working with the small-core singlemode
fibers that Kao had proposed, but some developers were considering
larger-core fibers that could collect light more easily. Bell had not changed
its plans for millimeter waveguides, which Kompfner still predicted would fill
the communication needs of major population centers through the 1980s.
Behind the scenes, the pressure was on at Bell Labs, 35 which still had not
matched Corning’s low-loss fibers. The stress highlighted tensions between
fiefdoms in the AT&T research bureaucracy. Miller wanted to draw fibers at
Crawford Hill, reasoning that as waveguides they fell into his communications
research domain. Murray Hill disagreed, believing that glass fell into its domain
of materials research. Eventually, upper management assigned glass
chemistry and fiber-making physics to Murray Hill but let Crawford Hill keep
experiments with novel fiber structures. 36
Groping for something they could demonstrate, Crawford Hill turned to
‘‘liquid-core’’ fibers, fine silica tubes filled with a dry-cleaning solvent, perchloroethylene,
C 2Cl 4. The liquid core guides light because its refractive index
is higher than pure silica, and the solvent was clearer than anything else Bell
could make. Crawford Hill measured loss of 13 decibels per kilometer, letting
them briefly claim the record for lowest reported fiber loss. 37 An Australian
group came up with the same idea independently and soon measured loss of
6.5 decibels per kilometer. 38 The University of Southampton later did slightly
better. 39 Nobody today admits seriously considering using liquid-core fibers in
communication systems; their problems were legion. However, they were useful
for laboratory tests of fiber transmission. 40
Miller also seized on an idea of Peter Kaiser’s, placing a flat planar waveguide
of pure silica inside a hollow silica tube and stretching it out into a
hollow fiber-like structure. Kaiser made samples, 41 but as with Karbowiak’s
thin-film waveguide, they worked much better in theory than in reality.
Murray Hill assigned more people to fiber development, but they lost time
shuttling back and forth to measure their fibers in Kaiser’s lab in Crawford
Hill. 42,43 This fast became a nuisance, so management asked a Murray Hill
optics specialist to design a new fiber measurement lab and funded it with
amazing speed. 44
At Crawford Hill, Miller shifted more people from hollow optical waveguides
to fibers. Their first task was to take a long, careful look at fiber technology.
No one knew if fibers would hold up over time. 45 Experimenting with
plastic coatings, Kaiser found they protected pure silica fibers from the environment,
and they remain standard on modern communication fibers. 46