City of Light: The Story of Fiber Optics

218 CITY OF LIGHT
rebuilding to provide two-way, high-capacity service with big pipes and good
switching.
That wasn’t an immediately fatal flaw in an era of urban planning and
Lyndon Johnson’s Great Society program. ‘‘New towns’’ projects, some government
funded, sought to build new communities in virgin territory. 4 Visionaries
hoped to make the new towns into ‘‘wired cities,’’ promising a more
equable, diverse, and democratic society. It was an enticing vision for a generation
of idealists disturbed by pollution, the Vietnam War, and the nuclear
arms race.
The Federal Communications Commission liked the idea of interactive television
and decreed in 1972 that future cable systems must provide two-way
service. No such systems existed at the time, but the National Science Foundation
agreed to sponsor three experiments starting in early 1974. The
technology worked, but high costs and unclear benefits later led the FCC to
drop its two-way requirements. 5
The Fibered City
In the heyday of ‘‘new town’’ planning, GTE Laboratories designed a network
to carry the usual array of futuristic services to a couple thousand homes.
The plan called for a separate coaxial cable to run from each home to a
central facility. The logistics of handling all those cables left John Fulenwider
aghast in 1972. Each cable was large, and a couple thousand would require
serious, bulky plumbing to connect to the equivalent of a telephone switching
office. A soft-spoken research engineer in his early forties with a passion for
jogging years before it was fashionable, Fulenwider had an eye for new technology
and had already spotted fiber optics. He knew fibers were thin and
flexible—and that a lot would fit into one 3/4-inch (1.9-centimeter) cable. 6
He sketched out a design for a fiber-optic network for the new town. Good
semiconductor lasers were not available, so he proposed using LEDs to send
signals to homes and bulkier solid-state lasers for the longer distances between
regional distribution centers. Four multimode fibers would run to each home.
Three would carry signals to the home, including color video-telephone, two
color television channels, FM radio, digital data, control signals, and two
ordinary voice phone lines. The fourth would carry signals in the other direction.
Like the telephone network, the fiber system would be switched, sending
users only signals they requested instead of all signals as in cable television.
7
The fundamental problem Fulenwider faced was network topology. Early
fiber systems ran between two points, but routing signals to many points was
much more difficult—even worse than for coaxial cables. It required many
transmitters, many receivers, many fiber connections, and ways to split signals
between fibers that did not yet exist. Fulenwider did his best, but costs
were discouraging. A GTE economist calculated his design would take seven
years to earn back the investment; the developer wanted a two-year payback.