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Everyone knows that radio waves can transmit information, so can light waves also transmit information? Light waves can transmit information through fiber optic cables, which is fiber optic communication. Can voice be transmitted using ordinary light? No. Only a faint grunt could be heard from such a light phone. The reason is that ordinary light is mixed with light of many different wavelengths (frequency) and has poor directivity. Using it to transmit voice is like a radio receiving programs of many frequencies at the same time. Various sounds are overlapped and transmitted to the receiver, making it impossible for people Hear the voice clearly.
In 1960, a young American physicist named Maiman invented a laser using ruby as an excited object, which produced a highly concentrated light with a single frequency direction, called a laser. Optical communication was only possible after the invention of the laser. But lasers travel through the atmosphere and are constantly attacked by rain, snow, fog and dust, and even a thin curtain of curtains can block the beam, rapidly diminishing the light's energy. How can the laser be transmitted to a distance without loss?
Once, a glass worker in Greece stumbled upon that light could not only travel rapidly from one end of a thin glass rod to the other, but also be very "tame", not radiating into the outer space of the rod at all, even though the thin glass rod is curved , it can also follow curved lines. After analysis, when the light hits the glass interface, a total reflection occurs.
The discovery inspired scientists to try thinly drawn glass fibers as "wires" for light. As a result of the experiment, no matter how the glass filament is bent, as long as the incident angle is appropriate, the laser light will be reflected back and forth in the glass filament, and will be "obediently" transmitted along the wire to the opposite end far away. The electrical signal of the image becomes an optical signal with corresponding intensity changes, and it can be transmitted to a distance along the optical fiber. When you speak into the microphone of the telephone, or when the camera captures an image, the sound or image is turned into an electric current, which is turned into a series of digital signals consisting of "0" or "1" (wherein "1" means there is 5 light, 0 means no light), the optical transceiver emits a string of light signals with different light and shade through the optical fiber, and transmits it to the other party's optical transceiver, where the receiving end restores it to a sound or image signal, and people in the distance can Hear the sound and see the image. This is how fiber-optic communication works.
The capacity of optical fiber communication is astonishingly large. On an optical fiber thinner than a human hair, tens of thousands of telephone calls or thousands of TV programs can be transmitted at the same time. If dozens or hundreds of optical fibers are formed into a fiber optic cable, the outer diameter is much smaller than that of the cable, but the capacity is increased by hundreds or thousands of times. Usually cables are made of copper or aluminum, and the price is not expensive, while the raw material of optical fiber is quartz, that is, sand, which is very rich in source. Optical fiber communication has good confidentiality and strong anti-interference ability, so it is widely used.
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