Chinese Americans, Dr. C.K.Kao Kun and Dr. C.A.Hockham, pointed out that if the impurities in glass can be completely removed, the loss can be reduced to 20 dB/km, which is equivalent to the level of coaxial cable. Then, optical fiber can be used for optical communication. Encouraged by this expectation, Corning Company finally produced an optical fiber with a loss of 20dB/km at 1970, thus paving the way for the development of optical fiber communication. It is found that the fiber has three low-loss transmission windows, namely, a short wavelength window of 850nm and a long wavelength window of 1300nm and 1500nm. Then, with the emergence of new manufacturing methods and the continuous improvement of process level, the fiber loss is decreasing. By 1979, the loss of single-mode fiber at 1550nm has dropped to 0.2dB/km, which is close to the theoretical loss limit of timely fiber.
Moreover, the frequency of light wave is high, and the bandwidth resources of optical fiber are also considerable, which is incomparable to any other transmission medium. It can be said that optical fiber is the ideal transmission medium that communication workers dream of, and its quality is almost perfect:
Almost unlimited bandwidth;
Almost zero loss:
Almost zero signal distortion
Almost zero power consumption
Almost zero material consumption
Take up almost no space
Almost zero price.
Therefore, optical fiber is the foundation of the information superhighway, which opens a new era of information revolution.