1966, Dr. Charles Kao, a British Chinese, published a famous paper, proposing for the first time that glass fibers with little light transmission attenuation can be obtained by solving the problems of purity and composition of glass.
Charles Kao graduated from London University in 1957 and began to study optical communication in 1965. He first studied the communication system with GaAs photodiode as the light source, and then studied the transmission medium of light, and found that the main difficulties were the large loss of light waves in the optical fiber medium, the fragile materials and the difficulty in manufacturing. So he solved the problem of light wave transmission loss by changing the composition, purity and structure of materials. The experimental results show that the impurity concentration in the timely glass is the main factor affecting the light wave attenuation. The light wave experiment with the wavelength of 65438 0 micron shows that the attenuation per kilometer is only 65438±0 dB. He obtained a lot of important data through repeated experiments, which laid a good foundation for writing papers. So a paper entitled "Insulated dielectric fiber surface waveguide for optical frequency" was published. He fully expounded the theoretical results and experimental results after years of hard exploration. The paper quickly attracted the attention and praise of scientists and engineers all over the world, and was widely introduced into practical application. 1970, Corning Glass Company of America successfully drew the first timely glass fiber with attenuation of only 20 decibels per kilometer for the first time. Since then, the fiber attenuation rate has been declining: 1974, 2 decibels per kilometer; 1976, per kilometer 1 decibel; 1979, 0.2 decibels per kilometer; In 1980s, it reached 0. 16 decibel per kilometer; Fluoride glass fiber developed in the 1990s has a lower attenuation, which has dropped to 0.03 dB per kilometer. This high-purity fluoride glass fiber has a very strong transmission capacity, with a transmission distance of 4,800 kilometers at a time, and can be used for intercontinental optical communication without relay stations. Today, it can be said that optical fiber has gone through a difficult course and achieved brilliant results.
The structure of the optical fiber is cylindrical, with a core with a diameter of 8 microns or 50 microns in the middle, which has a high refractive index, a cladding with a low refractive index and a plastic sheath outside, and the overall external diameter is 125 microns. Special manufacturing technology and special materials make the optical fiber as fine as silk, with high tensile strength and great compression resistance. In terms of performance, it has little attenuation to light waves, can transmit sounds, images and characters, has multiple functions, adapts to low temperature environment, and resists electromagnetic interference and radioactive radiation. Light wave propagates in optical fiber, does not radiate electromagnetic wave, and has extremely high security characteristics. Information travels at the speed of light, which is unparalleled. The capacity of optical communication is 1 ~ 1 100 million times higher than that of electric communication, and one optical fiber can transmit 65438 pieces at the same time. Optical fiber can be used not only for communication, but also for transmitting light energy; Can be used for manufacturing medical gastroscopes and industrial endoscopes, and has wide applications.