Introduction: His invention ushered in a new era of high-speed fiber-optic communications, bringing the world of internet and information to mankind, he is the optical fiber father-Charles Kuen Kao. September 23rd of this year, Charles Kuen Kao who died at 84, had a long connection to the communications industry.

Today, video calls can be made instantly by using high-speed fiber networks, even tens of millions of miles apart. Through the Internet, video and audio images can be reached at your fingertips, which is an unprecedented era. Optical fiber communication technology has reshaped the world. Looking back to the whole history of modern communications, there is a name how also cannot get past, and his invention opened a new era of high-speed optical fiber communication, bringing for the human with the Internet, information world, he is the father of optical fiber -- Charles Kuen Kao. September 23rd of this year, Charles Kuen Kao who died at 84, had a long connection to the communications industry.

 On October 6th, 2009, the Royal Swedish Academy of Sciences announced in Stockholm that it would award the 2009 Nobel Prize of physics to the British Chinese-born scientist Charles Kuen Kao. In his award speech, Charles Kuen Kao was clearly awarded for his breakthrough achievement in “the transmission of light in fibers for optical communication”. Former U.S. President Barack Obama said of Dr. Charles Kuen Kao, that he was proud of him and that the world owes him a great debt of gratitude for the work he did that completely changed the world and helped grow the world economy.

Even though the voices of doubt are everywhere, the original aspiration should not allow to change.

 Back in 1841, two scientists, Daniel Colladon and Jacques Babinet, did a seemingly simple but amazing experiment. They drilled a small hole in the barrel filled with water. Then, light the water over the barrel with a light. Finally, they were surprised to find that the luminous water flowed out from the hole of the bucket, and the water bent, and the light also bent, and the water succeeded in “capturing” the light. An experiment seems to be simple but revealing the fundamental principle of total reflection in fiber optics.

In 1959, the laser was invented, and its highly concentrated beam brought people with imagination. The information capacity of light as the transmission medium was 100,000 times higher than that of the traditional microwave system. So a large number of researchers began to study optical communication, in which Charles Kuen Kao was one of most obsessed. He firmly believes that optical communication has great potential and insists on looking for a transmission medium with extremely high transparency, because he believes that impurities in the transparent material are the main cause of excessive transmission attenuation rate, and if he solved the problem of attenuation in laser transmission, long-distance transmission would no longer be a problem.

Seven years later, in 1966, Dr. Charles Kuen Kao published a paper called as Dielectric Fiber Surface Waveguide Setting for the Transmission of Light Waves and he finally found out the answer. It was this landmark paper that led to his Nobel Prize in physics 43 years later. The paper proposed the original idea of using quartz glass for transmission, “as long as the concentration of iron impurity is reduced to one part per million, a glass material with a wavelength of 0.6 micron and a loss of 20dB/km can be made”, which can be used for long-distance signal transmission by such glass materials, according to the paper. 

Today, Dr. Kao’s vision has long been a reality, and fiber-optic cables have been installed all over the world. But at that moment, the voice of numerous questions was oncoming to Dr. Kao, and even some people said he is not polite to “dream”. Fortunately, Charles Kuen Kao was stubborn, constantly travelling the world to persuade glass manufacturers to develop new “pure glass”. At that time, most enterprises were reluctant to invest too much in the research and development of ultra-pure glass fiber due to its high cost and uncertain market prospect. 

New era was started finally after hard persuading.

Eventually, under untiring lobbying from Dr. Kao, the U.S. Company began to rely on kao’s published papers on optical fiber research and development. As a famous glass manufacturer in the United States and the most famous manufacturer of smartphone screen glass today, Corning made the world’s first low-loss experimental optical fiber in line with Kao’s theory in 1970, and the era of optical fiber communication finally came.

Subsequently, the optical fiber quickly became a big hit, and the industry invested a lot of manpower and financial resources, scientists, engineers went all out. At about the same time, a semiconductor laser using gallium arsenide (GaAs) as a pumping material was invented by Bell LABS and was widely used in optical fiber communication systems due to its small size. Optical fiber communication ushered in a golden period of development. 

Fiber produced by Corning adopted plasma-activated chemical vapor deposition (PCVD) process to manufacture fiber core layer. Meanwhile, a synthetic quartz tube manufactured by OVD process is used to form fiber cladding. Tube vapor deposition was a simple process developed by corning in 1970s. The chemical reaction mechanism of OVD process was flame hydrolysis, namely, the required core glass composition was obtained by layer by layer deposition of the “powder” generated by the gaseous halide (SiCl4, etc.) carried in the oxyhydrogen flame or methane flame. Combining the advantages of these two processes, Corning fiber had the advantages of precise refractive index distribution control, superior geometric characteristics and low attenuation.

“Charles Kuen Kao Star” still Shining 

In addition to his outstanding contributions to scientific research, Charles Kuen Kao has also achieved remarkable results in teaching and education. He joined the Chinese University of Hong Kong in 1970 and became head of the department of electronics; He was the third President of the Chinese University of Hong Kong (CUHK) from 1987 to 1996. Under Dr. Charles Kuen Kao’s leading, CUHK established the school of engineering, the school of education and several research institutes, laying a solid foundation for CUHK to become a world-class research university.

In 1996, the Purple Mountain Observatory of the Chinese Academy of Sciences named the asteroid "3463" as “Star of Charles Kuen Kao”. Nowadays, when looking up at the sky, we can’t forget that there was an old man who devoted his life to the field of communication, connecting the whole world together with a bunch of fiber optic cables.

 Today, more than 1 billion kilometers of glass fibers are laid underground and on the ocean floor, enough to orbit the earth 25,000 times and still growing at thousands of kilometers per hour. However, in the sky above, “Star of Charles Kuen Kao” still is shining as his smile. 

Source: Optical Fiber World