Dr. Kao received the Nobel Prize in physics for his research on the use of fiber optics in communications. (Bruce Dale/National Geographic/Getty Images)

Charles Kuen Kao, a researcher who perfected fiber optic communications in the 1960s, an advance that was credited with paving the way for the Internet and was honored with the Nobel Prize in physics, died Sept. 23 in Hong Kong. He was 84.

His death was announced by the Charles K. Kao Foundation for Alzheimer’s Disease in Hong Kong. Dr. Kao had been diagnosed with Alzheimer’s in 2002.

Dr. Kao grew up in Shanghai and, after the onset of the Chinese Communist Revolution, in Hong Kong. He was educated in England and conducted research across Europe and the United States in a career that made him known as the father of fiber optics.

He was working in Harlow, England, for a British subsidiary of the International Telephone and Telegraph Corp. in the 1960s when he made a surprising discovery about what he described as an “old, old idea.”

The “old idea,” he said in a biographical sketch for the Nobel Prize, was the transmission of light through glass — a process long used “for entertainment, for decoration, for short distances for surgery,” he noted, but not “over the long distances required for telephony.”

“Light passing through a rod of glass just fades out to nothing after a very short distance of a few feet,” he explained.

The new idea, credited to Dr. Kao and a colleague, was that the transmission of light could be improved enough to render existing copper-wire communications technology obsolete.

“Nobody bought my ideas,” Dr. Kao told CNN.com in 1999. “The prospect of producing something 1,000 times better than copper wire was very tempting. . . . When you are young, you are fervent about the things you believe in.”

Working with the British engineer George Hockham, he found that if impurities were removed from glass, light would travel through it with staggering efficiency. The fibers, thinner than human hair, were cheap to manufacture. With their capacity to transmit large quantities of data, they allowed photographs, music and other information to be sent around the world nearly instantaneously.

By the time Dr. Kao shared the Nobel Prize in 2009, the fiber-optic network was “the circulatory system that nourishes our communication society,” the Royal Swedish Academy of Sciences said in a news release at the time. “If we were to unravel all of the glass fibers that wind around the globe, we would get a single thread over one billion kilometers long — which is enough to encircle the globe more than 25,000 times — and is increasing by thousands of kilometers every hour.”

The other portion of the Nobel went to Willard S. Boyle and George E. Smith, researchers who were credited with developing the technology undergirding digital photography.

“These inventions may have had a greater impact on humanity than any others in the last half-century,” H. Frederick Dylla, director of the American Institute of Physics, told reporters when the prize was announced.

Dr. Kao sought to share credit with those who had applied his work to real-world uses in communication.

“I’m an engineer, so my real purpose is something that is useful,” he said in a 2004 interview with the Institute of Electrical and Electronics Engineers. “I still feel that it is not the invention of something that is important. It is how we can utilize that, then, to improve life that is important.”

Charles Kuen Kao was born to a landowning family in Shanghai on Nov. 4, 1933. His father was a judge, and his mother was a poet. He enjoyed what he described as a “very pampered and protected life,” with nursemaids and private tutors and recalled meeting his parents “as if for a daily royal audience.”

Dr. Kao had an early — even dangerously early — interest in chemistry that once led him to accidentally burn his brother’s pants with acid. “My parents were furious and confiscated all my chemicals, including the cyanide,” he said in his Nobel biographical sketch. “I wonder where they disposed of the stuff.”

After spending the post-World War II years in Hong Kong, Dr. Kao moved to Britain for his university studies in electrical engineering. He received a bachelor’s degree from Woolwich Polytechnic, now part of the University of Greenwich, in 1957, and a PhD from University College London in 1965.

In addition to his work with the Standard Telecommunication Laboratories, the ITT subsidiary in Harlow, England, Dr. Kao served as ITT’s executive scientist in the 1980s. He had a long association with the Chinese University of Hong Kong, where he helped found what became the electronic engineering department and served as vice chancellor from 1987 to 1996.

Dr. Kao, who held dual British-U.S. citizenship, received the Japan Prize in 1996. He had already begun his descent into Alzheimer’s disease when he was awarded the Nobel. Survivors include his wife of more than six decades, Gwen Kao, with whom he had two children.

Although his innovations helped make possible the exchange of information on the Internet, Dr. Kao said he did not spend a great deal of time online, and he offered a word of caution about the uses of his discoveries.

“Surfing the Web is time-consuming,” he told CNN.com. “When information is infinite, individual pieces of information are worth nothing.”