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Historical overview of optical communication methods Sadeq Adnan Hbeeb |
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Visual methods have been used to communicate extensively in the animal kingdom. There are clear examples of this, among animals that show signs of propulsion, spinning and warning of fierce attack. From the beginning of human civilization, humans used industrial optical light to transmit information to long distances. It used as an example, smoke signals or reflected sunlight during the day and smoke towers at night. Although there are more complex ways to transmit signals have been used at different times, and the use of towers only continued for centuries until the production of the semaphore at the end of the eighteenth century. At the same time, an electric telegraph was used to transmit information on land that competed with traditional methods using flags and light signals at the sea. Telegraph is a communications device used at the end of the 19th and early 20th centuries to transmit telegraphs and texts based on cryptographic characterization And sends it through wires to another that prints those pulses. In 1810, the American electrician Samuel Morse invented the telegraph that reprints the letters. However, these methods have been largely replaced by telephone and telegraph less. This was a major change in the form in which the information was sent and with the invention of optical fiber as a basic medium for transmission. It was the ideal alternative to copper substrates. The main material used in optical fibers is sand, which is cheaper than copper used in electrical systems. It is possible to say that optical communication was born with the invention of laser in 1958 and that the first development followed the actual production of the first laser in 1961. Since the laser beam is monochromatic to a high degree, And the wide bandwidth available for use, since the laser can be included only a fraction of its base frequency. So, it is natural to think that it can be used as a means of transmitting optical communications |
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