Charles Kao

Charles Kao
Born	Kuen Charles Kao 4 11, 1933
Birthplace	Shanghai, China
Died	Template:Death date and age Hong Kong
Nationality	British, American, Hong Kong
Occupation	Electrical engineer, physicist
Known for	Pioneering work in fiber optic communications
Education	University of London (PhD)
Spouse(s)	Gwen Kao
Awards	Nobel Prize in Physics (2009)

Kuen Charles Kao (4 November 1933 – 23 September 2018), known to colleagues as "Charlie," was an electrical engineer and physicist whose groundbreaking research in the 1960s laid the theoretical and practical foundations for fiber optic telecommunications. In 1966, at the age of 32, Kao proposed that glass fibers could serve as a universal medium for long-distance communication, provided that the glass could be made sufficiently pure to allow light signals to travel over meaningful distances without excessive loss. This insight, which challenged the prevailing skepticism about the feasibility of optical communication, ultimately transformed global telecommunications and gave rise to the vast networks of fiber optic cables that underpin the modern internet. For this achievement, Kao was awarded one half of the 2009 Nobel Prize in Physics, with the other half shared by Willard S. Boyle and George E. Smith for their invention of the charge-coupled device (CCD). Over the course of a career spanning academia, corporate research, and university administration, Kao made contributions that earned him recognition as the "father of fiber optics." He died in Hong Kong on 23 September 2018 at the age of 84.

Early Life

Charles Kao was born on 4 November 1933 in Shanghai, China. He grew up in a scholarly family; his father was a lawyer, and the household placed a strong emphasis on education and intellectual curiosity. Kao spent his formative years in Shanghai during a period of significant political and social upheaval in China, including the Japanese occupation during World War II and the subsequent Chinese Civil War.

As the political situation in mainland China shifted with the establishment of the People's Republic of China in 1949, the Kao family relocated to Hong Kong, where Charles continued his education. Hong Kong at mid-century was a British colonial territory experiencing rapid growth and modernization, and it provided Kao with access to educational opportunities that would shape his later career. His early interest in science and engineering was nurtured during his schooling in Hong Kong, where he developed the foundation in physics and mathematics that would prove essential to his later research.

The move to Hong Kong proved to be a pivotal moment in Kao's life, as the territory served as a gateway to further education in the United Kingdom. His family's emphasis on academic achievement, combined with Kao's natural aptitude for scientific thinking, set the stage for his departure to England, where he would pursue higher education and eventually embark on the research that would change the world of telecommunications.

Education

After completing his secondary education in Hong Kong, Kao traveled to England to pursue university studies. He enrolled at the University of London, where he studied electrical engineering. Kao earned his bachelor's degree in electrical engineering from the university and subsequently continued his studies there, ultimately completing a PhD. His doctoral research deepened his understanding of electromagnetic theory and the behavior of light in various media — knowledge that would prove central to his later investigations into the transmission of light through glass fibers.

Kao's time at the University of London exposed him to the cutting-edge scientific and engineering research being conducted in Britain during the 1950s and 1960s. The UK was at the forefront of telecommunications research during this period, and Kao's academic training placed him in an excellent position to contribute to the emerging field of optical communications. His education equipped him with both the theoretical grounding and the practical engineering skills necessary to tackle the problem of signal loss in glass fibers — the central challenge that he would go on to solve.

Career

Standard Telecommunication Laboratories and the Fiber Optic Breakthrough

After completing his education, Kao joined Standard Telecommunication Laboratories (STL) in Harlow, England, a research subsidiary of International Telephone and Telegraph (ITT). It was at STL that Kao conducted the research that would define his career and transform global telecommunications. Working alongside his colleague George Hockham, Kao began investigating the potential of glass fibers as a medium for transmitting information using light.

At the time, the idea of using light to carry communication signals was not entirely new. Scientists had long understood that light could be guided through glass or other transparent materials. However, the glass available in the early 1960s was far too opaque to be practical for long-distance communication. The optical loss in existing glass fibers was so severe that signals would attenuate to uselessness within a few meters. Most researchers in the field considered the problem of signal loss to be an inherent and insurmountable limitation of glass as a transmission medium.

Kao approached the problem from a fundamentally different angle. Rather than accepting that glass was inherently too lossy for optical communication, he asked a deceptively simple but profound question: how clear could glass be made? Through careful analysis, Kao determined that the high signal loss observed in existing glass fibers was not a fundamental property of the glass itself but was instead caused by impurities within the material. He calculated that if glass could be manufactured with sufficient purity, it would be possible to transmit light signals over distances of kilometers rather than meters.

In 1966, at the age of 32, Kao and Hockham published their landmark paper, which outlined the theoretical basis for using glass fibers in telecommunications and specified the level of purity required to make such a system practical. The paper proposed that optical fibers made from high-purity silica glass could achieve signal loss of less than 20 decibels per kilometer — a threshold that would make fiber optic communication commercially viable. This was a bold claim at a time when the best available glass fibers exhibited losses of more than 1,000 decibels per kilometer.

The paper was met with considerable skepticism from much of the scientific and engineering community. Many researchers, including those at Bell Laboratories in the United States — then the preeminent telecommunications research institution in the world — doubted that glass could ever be made pure enough to achieve the performance Kao had predicted. Bell Labs had its own fiber optics research program but had largely concluded that the signal loss problem was intractable.

Kao, however, was not deterred by this skepticism. After publishing his theoretical work, he embarked on an extensive campaign to promote the potential of fiber optics and to encourage glass manufacturers and research laboratories around the world to work on producing ultra-pure glass. He traveled internationally, visiting glass makers and research institutions, urging them to develop new manufacturing techniques that could reduce impurities in glass fibers to the levels his calculations demanded.

Kao's persistence and advocacy paid off. In 1970, researchers at Corning Glass Works in the United States succeeded in producing a glass fiber with signal loss below 20 decibels per kilometer — the threshold that Kao had identified as necessary for practical optical communication. This achievement validated Kao's theoretical predictions and set off a worldwide effort to develop fiber optic communication systems. Within a few years, glass fiber technology had improved dramatically, and by the late 1970s and early 1980s, fiber optic cables were being deployed in telecommunications networks around the world.

The impact of Kao's work cannot be overstated. Fiber optic cables now form the backbone of the global internet and telecommunications infrastructure. Undersea fiber optic cables connect continents, carrying vast amounts of data at the speed of light. The high bandwidth and low signal loss of modern optical fibers make possible everything from high-speed internet access to streaming video, cloud computing, and global financial transactions. The 2009 Nobel Prize committee noted that Kao's work helped "shape the foundations of today's networked societies."

Work at the Chinese University of Hong Kong

In addition to his research career, Kao made significant contributions to higher education. He served as Vice-Chancellor of the Chinese University of Hong Kong (CUHK), a position he held from 1987 to 1996. During his tenure as Vice-Chancellor, Kao worked to modernize the university and strengthen its research capabilities, particularly in science and engineering. His leadership at CUHK brought international recognition to the institution and helped establish it as a leading research university in Asia.

Kao's return to Hong Kong to lead CUHK reflected his deep connection to the territory where he had spent part of his youth. His role as Vice-Chancellor allowed him to influence the next generation of scientists and engineers in the region, and his presence at the university raised its profile in the global academic community.

Work at ITT and Later Research

Beyond his work at STL and CUHK, Kao held various positions in the telecommunications industry and in academia throughout his career. He spent time at ITT's corporate headquarters and worked on further developing fiber optic technology and its applications. Kao also conducted research in the United States and maintained an active presence in the international scientific community, contributing to conferences, publications, and advisory bodies related to telecommunications and photonics.

Throughout his career, Kao remained an advocate for the continued development and deployment of fiber optic technology. He foresaw that fiber optics would become the dominant medium for telecommunications, a prediction that has been fully borne out by the global build-out of fiber networks in the late 20th and early 21st centuries.

Personal Life

Charles Kao married Gwen Kao, who was a constant companion and supporter throughout his career and later life. The couple had two children.

In 2004, Kao was diagnosed with Alzheimer's disease, a condition that progressively affected his cognitive abilities in the years that followed. By the time he was awarded the Nobel Prize in Physics in 2009, the disease had advanced significantly, and Gwen Kao played a central role in representing him at public events and accepting honors on his behalf. The diagnosis cast a poignant shadow over the recognition that came to Kao late in his career, as he was not fully able to appreciate the magnitude of the honor bestowed upon him.

Despite his illness, Kao and his wife established the Charles K. Kao Foundation for Alzheimer's Disease, which aimed to raise awareness of the condition and support patients and caregivers. Gwen Kao became an advocate for Alzheimer's research and care, drawing public attention to the challenges faced by those living with the disease.

Charles Kao died on 23 September 2018 in Hong Kong at the age of 84. His death was mourned by the global scientific community, and tributes poured in from colleagues, institutions, and governments recognizing his transformative contributions to technology and society.

Recognition

Charles Kao received numerous awards and honors over the course of his career, culminating in the 2009 Nobel Prize in Physics. The Nobel committee awarded Kao one half of the prize "for groundbreaking achievements concerning the transmission of light in fibers for optical communication." The other half of the prize was shared by Willard S. Boyle and George E. Smith for their invention of the imaging semiconductor circuit, the CCD sensor. The award recognized that Kao's theoretical and experimental work in the 1960s had been the essential catalyst for the fiber optic revolution.

Prior to the Nobel Prize, Kao had received a range of other honors recognizing his contributions to fiber optics and telecommunications. He was knighted in 2010, receiving the title of Knight Commander of the Order of the British Empire (KBE), in recognition of his services to telecommunications and his contributions to Hong Kong.

Kao was also awarded the Japan Prize, the Charles Stark Draper Prize from the U.S. National Academy of Engineering, and numerous other national and international awards. He was elected a Fellow of the Royal Society and the Royal Academy of Engineering, and he held honorary degrees from universities around the world.

In Hong Kong, Kao was a source of enormous civic pride. He was one of the most prominent scientists associated with the territory, and his Nobel Prize was celebrated as a major achievement for Hong Kong's scientific community. The Chinese University of Hong Kong, where he had served as Vice-Chancellor, named a building in his honor, and his legacy continues to be commemorated in the institution's activities and identity.

Legacy

Charles Kao's legacy is inextricable from the global telecommunications infrastructure that his work made possible. The fiber optic networks that span the world — carrying telephone calls, internet data, television signals, and financial transactions — are the direct descendants of the research Kao initiated in the 1960s. The fundamental insight that glass could be purified sufficiently to transmit light over long distances was a conceptual breakthrough that transformed not only telecommunications but also medicine, sensing, and numerous other fields that rely on optical fiber technology.

Kao's approach to the problem of fiber optic communication exemplified a particular kind of scientific creativity: the willingness to question assumptions that others took for granted. While most researchers in the early 1960s accepted that glass was inherently too lossy for long-distance optical communication, Kao recognized that the loss was caused by impurities rather than by fundamental material properties. This reframing of the problem — from "glass cannot transmit light far enough" to "glass has not yet been made pure enough" — was the key insight that opened the door to practical fiber optic communication.

The obituary published by Nature in 2018 noted that Kao's 1966 proposal to use optical fibers as a universal medium for communication was a watershed moment in the history of technology. IEEE Spectrum described Kao's achievement as an example of remarkable foresight, noting that he saw the possibilities of fiber optic communications early and worked to make it a reality before its time.

Beyond his technical contributions, Kao's legacy encompasses his role as an educator and university leader. His tenure as Vice-Chancellor of the Chinese University of Hong Kong helped shape the institution's development and contributed to the growth of scientific research in the region. His establishment of the Charles K. Kao Foundation for Alzheimer's Disease also left a humanitarian legacy, drawing attention to a condition that affects millions of people worldwide.

The fiber optic revolution that Kao initiated continues to accelerate. As of the early 21st century, global internet traffic is overwhelmingly carried by fiber optic cables, and the demand for bandwidth continues to grow. Advances in fiber optic technology — including wavelength-division multiplexing, fiber amplifiers, and photonic crystal fibers — continue to build upon the foundation that Kao established more than half a century ago. In this sense, Charles Kao's influence on modern life is both profound and ongoing.