CHARLES KUEN KAO

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THE FATHER OF FIBRE OPTICS

In 1966, he and a young colleague, George Hockham, published an article that would later go on to become famous regarding the transmission of optical frequencies across the surface of dielectric fibres. The article to which they both put their name was the first step towards the development of a revolutionary breakthrough in the world of telecommunications: the optical fibre.

Although he shared the Nobel Prize with Boyle and Smith in 2009, his work had nothing at all to do with the CCD nor the way in which light images could be transformed into electrical current that could later be converted back into images. The breakthrough achieved through his work was the enabling of light to be transmitted along extremely fine fibres, similar to electrical cables but made of transparent glass rather than copper. Charles Kuen Kao is rightfully considered to be the father of fibre optics. Perhaps it is also fair that, as well as sharing half of the Nobel Prize with his colleagues, he also shares the title bestowed on them in a text that appears on the Swiss scientists’ own website explaining the decisions behind the award. In a clear display of admiration, the author of the text refers to all three of the pioneers, Kao, Boyle and Smith, as the “Masters of Light”.

HIS WORK ENABLED LIGHT TO BE TRANSMITTED ALONG EXTREMELY FINE FIBRES, SIMILAR TO ELECTRICAL CABLES BUT MADE OF TRANSPARENT GLASS RATHER THAN COPPER.

Kao was born in 1933 in the Chinese city of Shanghai where his father was a judge, having been educated at the Michigan Law School in Chicago. When Charles was 15 years old, his family had to flee to Hong Kong, which was a British protectorate at the time, in order to escape the war between China and Japan. Five years later, they moved to London where Kao graduated in Electrical Engineering and later earned a PhD from Imperial College London in 1965. In order to fund his studies, he had already started working in the company STC, a subsidiary of the American giant ITT. Soon afterwards, in 1966, he and a young colleague, George Hockham, published an article that would later go on to become famous regarding the transmission of optical frequencies across the surface of dielectric fibres. Hockman would later devote himself to theoretical problems involving radar and communication antennae. Some may say this was a shame because the article to which they both put their name was the first step towards the development of a revolutionary breakthrough in the world of telecommunications: the optical fibre.

Neither does it seem that Kao saw much potential in his original brilliant idea. In fact, four years after publishing the article, incidentally in a non-specialist magazine with a small circulation, he asked his company to grant him long-term leave to attend the Chinese University of Hong Kong, where he stayed for a few years until his company called him back. On his return, however, he was relocated to the parent company, ITT Corporation, and promoted to Scientific Director of the Electro-optical Laboratory in Roanoke in southern Virginia, where he would eventually go on the become the Director of Engineering. Despite the low-key nature of the magazine in which it was published, somebody obviously read the famous article, which has gone on to become one of the most cited works in research in the field, with over 200 citations in the most prestigious and far-reaching magazines. Another example of the ironies of science.

However, in essence, what did Charles Kuen Kao actually do to deserve a Nobel Prize many years later? The article that he wrote with Hockman was certainly read by more than one expert because, shortly after its publication, various companies were already trying to develop optical fibres along which different light frequencies could be transmitted, in the same way as various electromagnetic frequencies are transmitted along copper cables in telephones lines. And so it was in 1970 that the company Corning Glass Works managed to produce the first optical fibre for commercial use.

However, despite Kao’s belief that the problem with light transmission along very fine glass cable was not the attenuation of the light as it travelled along the fibre but rather the impurities in the glass itself, the first fibre optic cables only worked effectively over short distances. Problems with light dispersion persisted, as well as the more important issue of connections and forks between different cables when they formed part of a telecommunication network.

IN 1983, HE STATED IN AN INTERVIEW THAT, BEFORE LONG, THE OCEAN FLOOR WOULD BE COVERED IN SUBMARINE FIBRE OPTIC CABLES THROUGH WHICH THE ENTIRE WORLDWOULD COMMUNICATE.

Kao’s subsequent work always focused on resolving this type of problem. At the end of the 1970s, he demonstrated that the theoretical predictions that he had set out in the famous article in 1966 were, in fact, possible in practice. He always recommended the use of fibre optic cables made from the purest silica (silicon dioxide). He demonstrated that the signal attenuation could be reduced to just 5% per kilometre if the fibre was manufactured with the purest silica that technology could offer, compared to 99% losses over 20 metres in the first fibre optic cables produced. This was the challenge that he set himself. In fact in 1983, he stated in an interview that, before long, the ocean floor would be covered in submarine fibre optic cables through which the entire world would communicate.

In 1987, he left his job to return to the Chinese University of Hong Kong as its Chairman. Shortly after retiring, in 2004, he announced that he was suffering from Alzheimer’s disease, which prevented him from collecting his Nobel Prize in 2009. Later the same year, his children took him to live with them in California, where he still resides. Kao has triple nationality, holding citizenship status in China (or more precisely, Hong Kong), Great Britain and the United States.

The advent and rise of the internet as we know it today would obviously not have been possible without a range of contributions: new computer languages, email, the web, personal computers, mobile telephones, lasers and many more. Close to the top of the list, though, would have to be the optical fibre for its crucial role in establishing the immense lattice of intercommunications that makes up the mother of all networks, enabling billions of computers to interconnect efficiently without the transmission being affected by any external interference, as occurs with telecommunications using electromagnetic waves which can be interfered with by electrical cables or radio frequencies.