The 2009 Nobel Prize in physics has been awarded to three researchers whose work has formed the basis of modern telecommunications and digital imaging. The prize recognizes Charles K. Kao, whose discoveries led to a breakthrough in fiber optics, and Willard S. Boyle and George E. Smith, who invented the CCD (charge-coupled device) image sensor.
Optical fibers carry almost all telecom data and form the backbone of the Internet. “When combined with the laser and the transistor, the invention of an efficient, low-loss optical fiber has made nearly instantaneous communication possible across the entire globe,” H. Frederick Dylla, director of the American Institute of Physics, said in a statement.
The work was done in the mid-1960s. The invention of the laser in the early 1960s spurred researchers to develop a practical transmission medium for light, which can transmit data much faster than radio waves. Optical fibers, however, didn’t seem promising at the time because of their high rates of attenuation: only about 1 percent of the light sent through the fiber would be transmitted as far as 20 meters.
Kao’s insight was to focus not only on the physics of light, but on the material properties of the medium itself. In 1966, as a young engineer at Standard Telecommunication Laboratories in Harlow, U.K., Kao discovered the underlying causes of attenuation in optical fiber: iron impurities were causing it to absorb and scatter the light. Pure glass, he suggested, would make a better carrier and would also present cost advantages.
After further studies of how light of different wavelengths travels through different media, Kao and his colleagues pointed to silicon dioxide as the best material. But silicon dioxide is difficult to work with. A team of researchers at Corning Glass Works realized Kao’s designs in 1970, using a high-pressure reaction chamber to form the first low-loss optical fibers, and others at Bell Laboratories refined the manufacturing technique to bring down the cost.
Modern optical fibers are even better than what Kao predicted, losing just 5 percent of the light over a distance of a kilometer. In 1988 the first intercontinental optical fiber, which was 6,000 kilometers, was laid down between Europe and America; today there are over one billion kilometers of optical fiber around the world, with more being added each day.