How Glass Scientists Took on the Challenge of Harnessing Light
How Glass Scientists Harnessed Light
The information we sort through on our electronic devices each day seems to come out of nowhere. Just as we turn on a faucet and expect to get water, we assume the bandwidth is there to support our online communications demands.
But it’s the powerful, always-on capability of global optical fiber networks – enabled by more than two billion kilometers of thin glass strands– that ensure that we can post, chat, download, and transact with ease.
How did glass become the medium that harnessed light and transformed modern communications?
The revolution began in the mid-1960s, when most communications networks were based on copper wire, which transmitted signals electrically. Problem was, copper networks were severely limited in both speed and capacity for the growing communications needs of contemporary business.
Shifting from electrical to optical transmission looked intriguing, but early optical fibers couldn’t transmit light signals over long distances without loss of signal strength, a problem known as attenuation.
By 1965, the British Post Office developed a visionary plan to modernize its communications infrastructure. Post Office leaders turned to Corning Incorporated – already a noted leader in specialty glass innovations – to develop a low-loss optical fiber.
To meet their goals, Post Office officials weren’t looking for any modest fiber improvements. They would need an unheard-of 98% reduction in signal attenuation from other glass fibers available at the time.
Corning formed a small multi-disciplinary team of Ph.Ds to take on the daunting task: physicist Robert Maurer, chemist Peter Schultz, and engineer Don Keck. Maurer led and coordinated the effort. Schultz was in charge of glass composition. And Keck was in charge of actually measuring the light transmission and attenuation.
As with all experiments, there were many trials, many setbacks, and many late nights in the lab.
One of the biggest challenges was finding the right glass encasement, or cladding, for the fiber. Essential because its low refractive index confines light to the core of the fiber, the cladding needed to be thin, flexible, and inch-for-inch stronger than steel.
The team had an idea that if they could capture some of the soot generated by the high-temperature fiber manufacturing process, they could also nab a necessary additive called dopant.
Using an unlikely tool – an old vacuum cleaner – the scientists drew the soot out of the flame into the cladding tube, and it deposited on the inside wall. After intense heating, the soot would fuse to the inside of the fiber, a process called sintering.
The team predicted that the process would solve the problem of scattering and losing light.
They were right.
And in 1970, by doping the silica glass fiber with titanium, the inventors reached a breakthrough. They developed an optical fiber with attenuation of 17 decibels per kilometer – loss levels even lower than the 98%-reduction goal the British Post Office needed.
The innovation immediately established that optical communications could be practical.
And key milestones that followed the breakthrough firmly established glass optical fiber as the key enabler of the communications revolution:
Today’s optical fiber has dramatically improved in performance since its early days in the lab. Contemporary fibers have the ability to transmit the entire collection of the U.S. Library of Congress from Florida to London in under 25 seconds. It’s also three times stronger than steel, more durable than copper, and light and flexible.
With its unmatched speed and capacity, optical fiber is certain to remain at the heart of networks that are smoothly connecting growing data traffic around the world.