Optical fiber

In January 1966, Charles Kao and George Hockham at Standard Telecommunication Laboratories in Harlow, England, published a paper that would earn Kao a Nobel Prize forty-three years later. Their insight was simple but revolutionary: the problem with optical fibers wasn't the fiber design—it was the glass. If glass could be purified to remove the metal impurities that absorbed light, an optical fiber could theoretically carry 200 television channels or 200,000 telephone calls simultaneously. The goal was to achieve attenuation below 20 decibels per kilometer, far better than any glass fiber then available.

The adjacent possible for practical optical communication required the laser (demonstrated 1960), the concept of light guiding through total internal reflection (known since the 19th century), and crucially, Kao's recognition that glass purity rather than fiber geometry was the limiting factor. Previous researchers had dismissed glass fibers as too lossy for long-distance communication. Kao's contribution was identifying the path forward: create ultra-pure glass. He examined fused silica made by vapor deposition, the purest glass then available, and showed it had intrinsic loss low enough for telecommunications—if manufacturing contamination could be eliminated.

The race to achieve Kao's target engaged laboratories worldwide. In 1970, Robert Maurer, Donald Keck, Peter Schultz, and Frank Zimar at Corning Glass Works in New York achieved the breakthrough: they produced fused silica fibers with attenuation of only 17 dB/km, below Kao's 20 dB/km target. By 1972, Corning achieved 4 dB/km. By 1979, losses had dropped to 0.2 dB/km—approaching the theoretical limit imposed by quantum-mechanical scattering.

Why Corning? The company had decades of experience with specialty glass, including fused silica developed for high-temperature applications. When Kao published his paper identifying glass purity as the key challenge, Corning's materials scientists recognized they had relevant expertise. The vapor deposition process they had developed for other purposes proved adaptable to producing the ultra-pure glass cores that optical fibers required.

The first telephone-switching-office fiber links deployed in 1977. Through the 1980s, fiber became the backbone of global telecommunications. Undersea fiber cables replaced copper and satellite links for intercontinental communication. By 2025, there is enough optical fiber deployed to encircle the Earth more than 25,000 times. Every internet search, every video stream, every financial transaction traverses light pulses racing through glass fibers no thicker than a human hair.

Kao received the 2009 Nobel Prize in Physics 'for groundbreaking achievements concerning the transmission of light in fibers for optical communication.' When the prize was announced, he said, 'I am absolutely speechless and never expected such an honor.' The engineer who had shown that glass could be made pure enough to carry light had created the physical infrastructure of the information age.