Fiber Optic Cables How it works and how engineers use it to send signals Videos # 3 videos engineerguy I find this great: this is an optical fiber cable for a stereo. If you light this laser pointer on the end of the cable, it will direct the light to the other end. These cables are used to connect in our world today It is able to transmit information across countries and oceans, But first, let me show you how it works. I have a bucket that I modified by placing a slot in the interface. On the other side, I put a plug in this hole. I have a bottle of propylene glycol and a small amount of cream Ring holder And certainly a laser pointer Now, keep your eyes on this plug when I turn off the lights that’s cool.
Light traces the fluid stream all the way to the bucket. Amazing. This occurs because of the total internal reflection. When light enters the fluid stream is reflected As soon as it collides with the air-liquid interface. You can see here the first reversal, then the second and third. This occurs because there is a difference between the refractive index of the directed material They are propylene glycol here And between the outside Which represents air in this case. Remember that any time light hits a surface, it does Is absorbed by the material, Its reflection of them Or cross it in and through it We call the latter case a refraction It’s easier to see from the top view Reflection and refraction occur at the same time, But if light rays hit the surface at an angle greater than the critical angle The light will reflect completely and will not break. And in this propylene glycol and air system As long as the beam hits the surface at an angle greater than 44.35 degrees Which is measured from the perpendicular line, the light will move Through the duct by internal total reflection.
In order to have the same effect on fiber optics, engineers make glass pulp (usually pure silicon dioxide). And an outer layer called \ “cladding \” Which are also usually made of silicon dioxide, But with particles of boron and germanium to lower the refractive index. A 1 percent difference is enough to make optical fibers work. To make a long, thin piece of glass, engineers heat preformed glass Its center represents pure pulp glass and the exterior is cladding.
Then they pull the fibers by wrapping the solute around the wheel Speed up to 1600 meters per minute These tow towers are usually on several floors high The height allows the fibers to cool before wrapping them on the drum. One of the greatest engineering achievements was The first fiber optic cable to be stretched along the perimeter. As the TAT-8, it stretched from the Tuckerton area in New Jersey Track the ocean floor at a distance of 3,500 miles to branch out The Widemouth area in England and the Maimang region in France. The engineers carefully designed the cable to stay on the ocean floor.
At its center lies the pulp. With a diameter of less than one-tenth of an inch, it contains 6 optical fibers Wrapped around central steel wire. They are embedded in synthetic rubber to support the fibers They surrounded it with steel threads and then sealed it Inside a copper cylinder to protect it from water. The diameter of the last cable was less than one inch, However, it can carry 40,000 phone calls simultaneously. The summary of how to send information through a fiber-optic cable is very simple. When someone on the first party has code We may use Morse code We block the laser light where the person at the other end can see Flashes of light carry the message To transmit an analogue signal such as sound in phone calls, engineers use encoded pulsed modulation We take an analogue signal and cut it into sections Then we approximate the loudness or wave value as much as possible We want to convert this signal into a digital signal, Which means cut-off values for wave height and not just any value.
For example, I’m going to use four bits, So I have 16 possible wave height values. So the first four parts of the signal can be rounded With 10, 12, 14 and 15 We then take each section and convert its height into a series of zeros and ones. It becomes the first column with a value of ten after the encoding 0-1-0-1 We can do this for each part of the curve. Now, instead of looking at the green wave, Or even blue columns, We can imagine the signal as a string of Zeros and ones are sorted by time This is the order we send through the fiber optic cable.
Send a flash that represents the one and its number represents zero. Certainly, the same encoding method used is known at the receiving end It is easy to decrypt the message Now, you might be wondering how laser pulses can travel nearly 4,000 miles Across the ocean. They cannot do this without help because the light will be able to pass through the sides of the fibers.
Let’s look at the propylene stream. Thus the light weakens as it passes. You can see here a narrow beam in the bucket, Expands slightly when it enters the yard. After the first bounce, the beam leaves wider than it was. This is because the interface with air is not flat. The beams forming the beam beam collide at somewhat different angles. When the beam beams collide for the second time, individual rays diverge further and further Even when the rays reach the third collision, they are not At the critical angle and you can get out of the sides of the stream. And here it happens in a few inches, But in a cable such as TAT-8 leaves the signal 50 kilometers before you need to zoom in. Absolutely stunning. I’m Bill Hamak, an engineering boy.
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