The glass had to get purer, and somebody had to work out how much purer. In 1966 Charles Kao calculated how to transmit light over long distances through . The fibers then available carried a signal about twenty meters. Kao showed that with glass of sufficient purity the distance would be a hundred kilometers.
The calculation was the contribution. Nothing had to be invented first, because the obstacle was the loss of light in the material rather than any missing component. Kao’s enthusiasm persuaded other researchers to take the goal seriously, and the first followed just four years later, in 1970. He shared the 2009 Nobel Prize in Physics for the work.
In 1966 Charles Kao produced a calculation rather than a device. He worked out carefully how to transmit light over long distances through optical glass fibers, and what the glass would have to be like. With a fiber of the purest glass, he showed, it would be possible to send light signals over a hundred kilometers. The fibers available in the nineteen sixties managed about twenty meters.
That gap is the whole story of the following decade. The obstacle was not the idea of guiding light down a thread, which was already understood, but the loss of the signal inside the material. Kao’s enthusiasm inspired other researchers to share his vision of the potential of fiber optics, and the first ultrapure fiber was fabricated successfully just four years later, in 1970.
The Royal Swedish Academy awarded him half the 2009 Nobel Prize in Physics for groundbreaking achievements concerning the transmission of light in fibers for optical communication. The other half went to Willard Boyle and George Smith for the CCD sensor, which is a neat pairing: one half of the prize for capturing images and the other for moving them.
The academy’s description of what followed is not modest. These glass fibers make up the circulatory system nourishing our communication society, and they support global such as the Internet. Light flows in thin threads of glass carrying almost all telephony and data traffic, so that text, music, images and video can be transferred around the globe in a split second. One caution: a prize citation explains why an award was given, which is not the same as a technical history of who did what.
wat. Before 1966 glass carried light twenty meters; the calculation said it could carry it a hundred kilometers.
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It is a case where a number came before a technology. The target existed on paper for four years before any glass met it, and the industry grew out of knowing what to aim at.
How do we know?
The Royal Swedish Academy of Sciences press release for the 2009 physics prize sets out Kao’s 1966 calculation and the distances achievable before and after. It also gives the date of the first ultrapure fiber.
What is still unknown
A prize citation written to explain an award, not a technical account. It gives round figures for distances and credits one calculation in a field with many contributors.
Learn something?
Where to next
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