how do fiber optic cables work ?

Fiver optics ?

You have heard of them ?

Yes you must have !

So here's a full guide about fiber optic cables !

Fiber optic cables are replacing copper wiring to increase the speed of digital information transmission. These cables are bundles of extremely pure glass threads that have been coated in two layers of reflective plastic. A light source -- typically a laser -- switches on and off rapidly at one end of the cable to transmit digital data. The light travels through the glass strands and continuously reflects off of the inside of the mirrored plastic coatings in a process known as total internal reflection. Systems based on fiber optics can transmit billions of bits of data per second, and they can even carry multiple signals along the same fiber by using lasers of different colors.

Fiber optics (optical fibers) are long, thin strands of very pure glass about the diameter of a human hair. They are arranged in bundles called optical cables and used to transmit light signals over long distances.

If you look closely at a single optical fiber, you will see that it has the following parts:

• Core - Thin glass center of the fiber where the light travels
• Cladding - Outer optical material surrounding the core that reflects the light back into the core
• Buffer coating - Plastic coating that protects the fiber from damage and moisture

Hundreds or thousands of these optical fibers are arranged in bundles in optical cables. The bundles are protected by the cable's outer covering, called a jacket.

Optical fibers come in two types:

• Single-mode fibers
• Multi-mode fibers
• Over the last 20 years or so, fiber optic lines have taken over and transformed the long distance telephone industry. Optical fibers are also a huge part of making the Internet available around the world. 
• To understand how a fiber optic cable works, imagine an immensely long drinking straw or flexible plastic pipe. For example, imagine a pipe that is several miles long. Now imagine that the inside surface of the pipe has been coated with a perfect mirror. Now imagine that you are looking into one end of the pipe. Several miles away at the other end, a friend turns on a flashlight and shines it into the pipe. Because the interior of the pipe is a perfect mirror, the flashlight's light will reflect off the sides of the pipe (even though the pipe may curve and twist) and you will see it at the other end. If your friend were to turn the flashlight on and off in a morse code fashion, your friend could communicate with you through the pipe. That is the essence of a fiber optic cable.
  Making a cable out of a mirrored tube would work, but it would be bulky and it would also be hard to coat the interior of the tube with a perfect mirror. A real fiber optic cable is therefore made out of glass. The glass is incredibly pure so that, even though it is several miles long, light can still make it through (imagine glass so transparent that a window several miles thick still looks clear). The glass is drawn into a very thin strand, with a thickness comparable to that of a human hair. The glass strand is then coated in two layers of plastic.
  
  By coating the glass in plastic, you get the equivalent of a mirror around the glass strand. This mirror creates total internal reflection, just like a perfect mirror coating on the inside of a tube does. You can experience this sort of reflection with a flashlight and a window in a dark room. If you direct the flashlight through the window at a 90 degree angle, it passes straight through the glass. However, if you shine the flashlight at a very shallow angle (nearly parallel to the glass), the glass will act as a mirror and you will see the beam reflect off the window and hit the wall inside the room. Light traveling through the fiber bounces at shallow angles like this and stays completely within the fiber.
  Okay so here how it transmits bits and bytes 
  So there is a laser at one end of the optic and at another end there is a sensor, think of the laser is turned on then it represents a bit (1) for the sensor and of it is turned off another(0) this turn on and turn off are done several billion times in a minute to transfer the bits !!and then these bits are transformed into codes and machine language etc
  Modern fiber optic cables can carry a signal quite a distance -- perhaps 60 miles (100 km). On a long distance line, there is an equipment hut every 40 to 60 miles. The hut contains equipment that picks up and retransmits the signal down the next segment at full strength.