In the 1960s, Charles Kao often annoyed his wife, Gwen, by coming home late for dinner.
Dr. Kao, a refugee from the Chinese Communist revolution, told her his research for a British subsidiary of International Telephone & Telegraph Corp. could change the world one day.
Oh, really, his wife later recalled saying with a dash of sarcasm. So youll get the Nobel Prize, will you?
That didnt happen until 2009, long after Dr. Kao really did change the world.
In a 1966 paper written with George Hockham, he outlined the potential for using pulses of light to carry huge volumes of voice and data signals long distances through strands of glass that became known as optical fibers. Few took him seriously until several years later, when Corning Glass Works found ways to do just that.
Fiber-optic cables began carrying telephone signals in the late 1970s. By the 1990s, a global mesh of fiber optics had made the internet possible and turned copper telephone wires into relics.
When people stream video at the beach, they tend to thank wireless technology. Few recognize the role of Dr. Kao. Its a little silly we call it the wireless industry, said Daniel Berninger, a communications-network architect. Theres nothing wireless in the network except for that distance from your phone to the nearest cell tower, where optical fibers take over.
By the time he got his Nobel, Dr. Kao was suffering from Alzheimers disease and had trouble speaking. He died Sept. 23 in Hong Kong at the age of 84.
Kao Kuen, who adopted the English name Charles, was born Nov. 4, 1933, in Shanghai. His father, who attended law school in Michigan, was a judge. His parents, whose first two children died of measles, pampered him, hired tutors and didnt send him to school until he was 10.
Maybe it was the home tutoring, or the late start to formal schooling, or an overly cautious and protective upbringing, he was quoted as saying in his Nobel biographical note, but in any case I never became a talkative person. As an adult I am not always comfortable in social gatherings with small talk.
As Chinese Communists battled Nationalists in 1948, his family fled to Hong Kong, where Charles finished high school. Naturally curious, he used phosphorus to make exploding mud balls and once accidentally splashed nitric acid on his little brothers trousers, prompting his parents to impound his chemicals.
During a six-week sea voyage to England, where he would study electrical engineering at Woolwich Polytechnic, he met a professor who passed the time at sea teaching him quantum mechanics. Upon arrival in London, disappointed by the meager provisions at his London boardinghouse, he developed a taste for fish and chips.
After finishing his undergraduate degree in 1957, he got a research job at Standard Telephones & Cables, a British unit of ITT, and later earned a doctorate from University College London.
Though scientists were excited about the potential of light beams to carry data, it was unclear how to do it. Efforts to send laser signals through open air ran into interference from the weather, causing the beams to bounce around, as Dr. Kao put it. Another approach, streaming light pulses down hollow tubes, proved overly complicated.
Transmission through glass strands was seen as another possibility, but impurities in glass available at the time meant light signals could travel only a few yards. Dr. Kao calculated the degree to which impurities could be reduced. He concluded it would be difficult but not impossible to create sufficiently pure glass. So it proved.
The key, wrote Jeff Hecht, the author of a history of fiber optics, was Kaos question. He asked what was possible to do, not what had been done.
In an oral history recorded in 2004, Dr. Kao described his landmark 1966 paper as the result of a bit of detective work as well as good theory and good fundamentals. So there was really nothing spectacular.
Dr. Kao spent 30 years at various units of ITT, including a posting in Roanoke, Va., and became director of corporate research. He later was vice chancellor of the Chinese University of Hong Kong.
His family established the Charles K. Kao Foundation for Alzheimers Disease to educate the public and improve care.
Dr. Kao was once asked how long fiber optics would be used. Nothing better was likely to come along for 1,000 years, he said. But dont believe what I say, he added, because I didnt believe what experts said either.