You might have noticed in “Introduction to Optical Fibers and Fiber Optics“, we used the term light pipe to describe an optical fiber. An optical fiber transmitting light can be analogous to pipe carrying water. Daniel Colladon and Jacques Babinet demonstrated the guiding of light by refraction in 1840 in Paris. Guiding of light by refraction is the basic principle of fiber optic communication.
Daniel Colladron mentioned about “light pipe” or “light fountain” in an article about his study of behavior of light rays inside a parabolic liquid stream. That article was published in 1842. That article titled “On the reflections of a ray of light inside a parabolic liquid stream” he described how light can be confined to follow the shape of its medium. In 1852, John Tyndall demonstrated the behavior of light to obey its medium in London. In his book about the nature of light, John Tyndall wrote about Total Internal Reflection, the underlying principle of fiber optics communication.
In 1880 Alexander Graham Bell and Sumner Tainter demonstrated the working of first Photophone at the Volta Laboratory in Washington, D.C., to transmit voice signals over light beam. At that time the photophone was an advanced form of telecommunications, though subjected to atmospheric interferences.
Clarence Hansell, who was an experimenter in radio and John Logie Baird, who was a pioneer in television demonstrated image transmission through tubes during 1920s. Close internal illumination of mouth in dentistry began in early twentieth century. Dr. Heinrich Lamm used the image fibers for medical examinations. During the 1940s glass optical fibers having a cladding layer were used for imaging purpose. Applications of optical fibers were focused for imaging during that time. Developments in optical fibers were proceeding towards fiber bundles. In 1954, Harold Hopkins and Narinder Singh Kapany published an article in the journal Nature titled “A flexible fiberscope, using static scanning”. Their experiment in Imperial College in London showed the low loss light transmission through 750 millimeters long fiber bundle. In 1956, three researchers at the University of Michigan, Lawrence E. Curtiss, C. Wilbur Peters and Basil Hirschowitz got patent for their fiber optic semi flexible gastroscope that was first of its kind. The development process of this gastroscope witnessed the development of first glass clad optical fibers. Until then cladding materials were impractical oils and waxes that had lower refractive index than core glass material. The invention of semi flexible gastroscope triggered developments in optical fibers especially in imaging techniques.
1963, a Japanese scientist Jun-ichi Nishizawa, who was working with Tohoku University, proposed the use of optical fibers for communications. Nishizawa invented other technologies that lead to the development of graded-index optical fiber as a channel for transmitting light from semiconductor lasers. In 1965 Manfred Borner, a German physicist at Telefunken Research Labs in Ulm demonstrated the working of fiber optic data transmission. He applied to patent this technology in 1966. A major breakthrough in optical communication happened when Charles K Kao and George A. Hockam of Standard Telephones and Cables, a British company proposed and promoted the idea that the attenuation in silica optical glass fibers could be reduced below the 20 dB/km. This proposal gave encouragement to the researchers to achieve low attenuation in optical fiber that would make the optical fibers suitable for telecommunication.
Charles Kao got Nobel Prize in Physics (in 2009) for his discovery. The team proposed and theorized the right methods to reduce attenuation in optical fibers. Apart from scattering loss, impurities in silica optical fibers penalize heavily on attenuation. Kao’s researches towards purifying the glass found success.