Sir Charles ‘Charlie’ Kao died on 23 September 2018, aged 84. He is recognised as the ‘father’ of modern optical fibre communications, based on his work at Standard Telecommunication Laboratories (STL) in Harlow, Essex.
His work was described in a talk at IEE Savoy Place (now the IET) and published in IEE Proceedings in July 1966.
It was Charlie’s observation, reportedly based on noticing the bright transmission in silica rods, but then backed up with careful measurement, that vapour-grown fused silica could be used to make low-loss optical fibres. His findings caused the work on fibre communications worldwide to explode.
Charlie’s paper with the late George Hockham in 1966, not only pointed this out, but described the single mode design that we mostly use today.
At a time when people were struggling with conventional glasses (and liquids) for fibre, with losses hundreds of times higher, this was an amazing and inspiring breakthrough. Charlie was awarded the Nobel prize in physics in 2009 and was knighted a year later.
Today we are installing over 300 million km (a thousand times the Earth-Moon distance) of silica fibre, of the type Charlie envisaged, every year.
The vast bulk of communications runs on Kao-style optical fibre for most of its distance. This includes all wireless and mobile devices like smartphones, and all communications within the vital data centres that support web services. The optical fibre has enabled the internet and communications revolution, and does most of the heavy lifting.
Charlie was a great man and by his own description a “citizen of the world." Born in China, where he also worked, he married a British engineer, and was also a citizen of the UK and the USA.
He was an inspiring person, and was always encouraging and supportive of young researchers. Though an intellectually big human being, he contributed personally to make the world a smaller and more accessible place.
Charlie’s professional community will remember him with much pride and affection. The week after he died, we held a short silence for him at the >8,000 attendee ECOC big optical fibre conference, which started at the IET in 1975.