From Curiosity to Cornerstone of Modern Life
It is easy to forget just how extraordinary glass is. We see it in windows, bottles, glasses and countless everyday objects, yet some of the most important glass in the modern world is almost invisible.
Stretch a strand of glass thinner than a human hair across the ocean and it can carry thousands upon thousands of telephone conversations, films, financial transactions and internet messages – travelling as pulses of light.
From ancient glassmakers experimenting with fine strands to the vast fibre-optic networks carrying the world’s digital traffic today, this is one of the great – and surprisingly little-known – stories in the history of glass.
From Ancient Curiosity to Modern Material
Glass fibre is certainly not a recent invention. Ancient craftsmen discovered that glass could be drawn into fine threads, using them for decoration and ornamentation. For centuries, however, glass fibres remained something of a curiosity rather than an engineering material.
That changed dramatically in the early 20th century.
During the 1930s, American researchers developed methods of producing fine, continuous glass filaments on an industrial scale. Companies including Owens-Illinois and Corning Glass Works played important roles in developing and commercialising the technology.
Suddenly, glass was no longer simply something to look through, drink from or admire. It could be spun, strengthened and engineered.
Glass fibre found an immediate role as reinforcement. Combined with resins, it produced the material we now know as fibreglass – strong, lightweight and resistant to corrosion.
Boats, cars, buildings, aircraft and, later, wind turbines would all benefit from this remarkable combination of glass and polymer.
But glass had another trick up its sleeve.
It could carry light.
The Day Glass Learned to Carry Light
The principle behind fibre optics is beautifully simple.
In the 19th century, scientists demonstrated that light could be guided along a curved path by exploiting a phenomenon known as total internal reflection. In 1854, the British physicist John Tyndall famously demonstrated the principle using a stream of water: light followed the curved stream rather than travelling in a straight line.
The idea that light could be guided through glass followed naturally.
By the 1950s, researchers were developing bundles of optical fibres capable of carrying images. Among the pioneers was Narinder Singh Kapany, who is widely associated with the development of fibre optics and is credited with coining the term itself.
There was, however, a problem.
The glass was simply not good enough.
Light travelling through early fibres disappeared rapidly, making them unsuitable for sending information over long distances.
The British Breakthrough
The crucial breakthrough came in Britain.
In 1966, Charles Kao and George Hockham, working at Standard Telecommunication Laboratories, published a landmark paper arguing that the problem was not with the principle of optical communication but with impurities within the glass itself.
If glass could be made sufficiently pure, they reasoned, light could travel through it for kilometres rather than merely metres.
It was a deceptively simple observation with enormous consequences.
Kao’s work ultimately earned him the 2009 Nobel Prize in Physics, recognising his groundbreaking contribution to the transmission of light through fibres for optical communication.
The challenge was now handed to the glassmakers.
Corning Turns Theory into Reality
In 1970, researchers at Corning Glass Works produced a low-loss optical fibre capable of transmitting light over much greater distances.
The age of fibre-optic communications had begun.
From that point onwards, progress accelerated. Manufacturing techniques improved, glass became purer, lasers and LEDs provided practical light sources, and increasingly sophisticated methods were developed for sending multiple signals simultaneously through the same fibre.
One particularly important development was the erbium-doped fibre amplifier, which enabled optical signals to be amplified without first converting them back into electrical signals.
In other words, the glass itself had become part of the communications system.
From Glass to the Internet
During the 1980s and 1990s, fibre-optic networks spread rapidly across countries and beneath oceans.
Today, enormous submarine cables connect continents, carrying the world’s international communications. The emails we send, the films we stream, the financial transactions we make and the information stored in cloud data centres all depend upon this extraordinary infrastructure.
And what makes it particularly remarkable is its scale.
A cable carrying enormous volumes of information may contain optical fibres no thicker than a strand of hair.
The internet may appear to exist in some mysterious digital cloud, but much of it is actually travelling through very real glass.
Glass at the Heart of Modern Life
Fibre optics is no longer simply about telephone calls and internet connections.
Data centres use vast quantities of optical fibre to move information between computers and servers. Mobile phone networks depend upon fibre connections to carry data between cell sites and the wider network. Medical technology uses fibre optics for endoscopy and laser treatments.
Optical fibres can even become sensors.
They can be used to monitor bridges, pipelines, aircraft and other structures, detecting changes in strain, temperature or vibration.
And there is another fascinating connection.
The same fundamental material that carries light across the world can also provide physical strength.
Glass-fibre-reinforced composites are now found in everything from aircraft components and automobiles to sporting equipment and construction materials. Perhaps most visibly, enormous wind turbine blades rely heavily on glass-fibre composites to provide strength without making them impossibly heavy.
So glass fibre has developed two extraordinary careers:
It can carry light – and it can carry loads.
Why Fibre Optics Has Changed Everything
Compared with traditional copper communications, optical fibre offers enormous bandwidth, very low signal loss and immunity to electromagnetic interference.
And as our appetite for data continues to grow, those characteristics become increasingly important.
Streaming, cloud computing, connected devices, artificial intelligence and ever more data-hungry applications are placing unprecedented demands on communications networks.
The answer, remarkably, is still glass.
What Comes Next?
The story is far from over.
Researchers are investigating hollow-core fibres, in which light travels through a central air-filled region rather than entirely through solid glass. Other developments are increasing the amount of information that can be transmitted through individual fibres, while huge programmes of fibre deployment continue to bring high-speed broadband to homes and businesses.
As artificial intelligence and cloud computing consume ever greater quantities of data, the demand for optical communications is likely to increase still further.
The humble glass fibre is therefore being asked to do something extraordinary: carry ever more of the world’s information, ever faster, through an almost impossibly small strand of glass.
A Remarkable Glass Story
For members of the Glass Sellers’ Company, there is something particularly satisfying about this story. Glass is sometimes regarded as an ancient material – beautiful, useful and perhaps rather traditional. Yet here is the same fundamental material at the very heart of the 21st century.
From the decorative glass threads of ancient craftsmen, through the development of fibreglass, to the pure silica fibres carrying the internet beneath our oceans, glass has repeatedly reinvented itself. It has become insulation, reinforcement, medical technology, communications infrastructure and the invisible highway of the digital age.
Not bad for a material made principally from sand.
And perhaps that is the enduring magic of glass: just when we think we understand what it can do, it finds another way to surprise us.
