City of Light: The Story of Fiber Optics

194 CITY OF LIGHT
but the infusion of cash from Philips was reviving Valtec, helping it build a
solid technical reputation. 84
Phone companies began shifting their interest to the longer wavelength to
run long distances. The change came as Saskatchewan Telecommunications
was building a 3400-kilometer (2100-mile) loop to carry a dozen digital video
signals to the largest towns in the prairie province. Project manager Graham
Bradley bet boldly on fiber and contracted for the best available fiber systems.
Construction started in 1980 with a first-generation system but soon shifted
to 1.3 micrometers over longer distances. 85
The longer wavelength roughly doubled transmission speed and distance
through graded-index fibers. Second-generation systems spread fastest where
those capabilities were critical, as in rural Canada. First-generation systems
remained in the pipeline, with many potential customers wary about shifting
to new systems that used costly new lasers with little track record. The consensus
of telephone companies remained solidly in favor of graded-index fibers
for the same reasons Stew Miller had advocated them years before—their
large cores collected light easily.
A Fateful Trial at British Telecom
Doubts about graded-index systems were growing in the labs. They ‘‘are exceedingly
complex,’’ John Midwinter complained as he reviewed the state of
the art circa 1980. 86 The Post Office was splitting off its telephone division as
British Telecom, and Midwinter was tired of battling mode monsters. He wondered
how far 140 million bits per second could go through single-mode fiber
at 1.3 micrometers, so his group set up a laboratory test to find out.
The answer was 49 kilometers (30 miles). ‘‘That sent shock waves through
British Telecom,’’ recalls Midwinter. There were buildings about every 30
kilometers (19 miles) along the company’s long-haul phone lines, originally
built to provide electrical power to repeaters on coaxial cables. With singlemode
fibers, repeaters could be put in those buildings and kept out of dingy
manholes, making the system simpler and more reliable. The demonstration
‘‘suddenly made people realize that graded index was a dead duck,’’ recalls
Midwinter. 87 That was not what people scaling up production of graded-index
fiber wanted to hear.
Midwinter’s boss, Sidney O’Hara, wanted to go single-mode immediately
in 1981. Despite his frustration with graded-index fibers, Midwinter urged
caution because a few problems remained with single-mode fibers. 88 His talented
team tackled the problems head on and made rapid progress. They
collaborated with Standard Telecommunications Labs on a single-mode trial
between Martlesham and Ipswich in 1982. The results were impressive.
Single-mode fiber carried 565 million bits per second—then the highest speed
used in European telecommunications—62 kilometers without repeaters at
1.3 micrometers. Their signal went even farther, 91 kilometers at 1.55 mi-