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Optical Fibres Explained In 2 Minutes

posted Dec 8, 2017, 12:49 PM by Rohit Bhaskar   [ updated Jul 10, 2018, 11:51 AM by Chirag Trasikar ]

Ever thought that light can be used to carry messages and for communications between two or more devices ? Did you know the internet which you get you comes in the form of light ? How’s this possible? 
Ans. Optical Fibre!!
This post is going to be extremely interesting for communication engineers! :)  So let's begin

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. When fiber replaces copper for long distance calls and Internet traffic, it dramatically lowers costs. 

An optical fibre is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Unlike copper wire based transmission where the transmission entirely depends on electrical signals passing through the cable, the fiber optics transmission involves transmission of signals in the form of light from one point to the other. Furthermore, a fiber optic communication network consists of transmitting and receiving circuitry, a light source and detector devices like the ones shown in the figure below.

When the input data, in the form of electrical signals, is given to the transmitter circuitry, it converts them into light signal with the help of a light source. This source is an LED or a laser whose amplitude, frequency and phases must remain stable and free from fluctuation in order to have efficient transmission. The light beam from the source is carried by a fiber optic cable to the destination circuitry wherein the information is transmitted back to the electrical signal by a receiver circuit.

Working of Fiber optic communication:

The Receiver circuit consists of a photo detector along with an appropriate electronic circuit, which is capable of measuring magnitude, frequency and phase of the optic field. This type of communication uses the wavelengths near to the infrared band that are just above the visible range. Both LED and Laser can be used as light sources based on the application.

To understand in a simple way 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 flashlights 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.

This is a 2 minute explanation of how communication takes place by optical fibre. Optical fibre are also used for medical,defence and a lot more purposes.The advantage offer by this over other means is the large amount of data which can be sent over long distance more efficiently at faster rate reliably. The loss of information and distortion is negligible.

Hope you understood!

- Yash Hule