How Optical Fibers Transmit Messages?

Optical fiber is thin, long silica or plastic, cylindrical in structure that has found its applications in telecommunications, sensors, health industry, imaging etc. The extremely small diameter of silica rod provides extra benefits to the products made out of it. This thin cylindrical rod of silica or plastic material can be used as optical waveguide, meaning that it can guide light through it.

With the invention of optical fibers and use of light for transmission of communication signals, long distance high bit rate transmission became possible. Thus optical fibers became an improved alternative for metallic copper cables that used electricity to carry signals. Deployment of first generation optical fiber networks had started coming up during the 1970’s.

Optical fiber is a solid pipe of silica or plastic. Silica optical fiber is used for long distance telecommunications. I Stress once again that the silica rod is solid and cylindrical. There are people who have doubt that how a medium transmit telephone sound through it if it is solid in structure? They think optical fiber is like a pipe having hollow path in the middle as shown in the below diagram.


If there is no hollow path, how the sound waves will travel through an optical fiber? Solid cylindrical glass rods carrying data (voice, image, video, text etc) in the form of light is something that cannot be visualized or imaginable for at least some people. One of my colleagues, who was working in optical fiber drawing tower had hard time convincing a college student, who visited the drawing tower as part of his project went in to the mood of questioning my friend’s authority in fiber optics when my friend told him that the optical fiber does not have hole inside! That was in 1996, a time, fiber optics started spreading to developing countries too.

Yes, Optical fiber is a solid cylinder of glass or plastic. They do not have hole to carry our voice. The sound is not directly passed through an optical fiber. The sound is first converted in to electricity, then to light to send through an optical fiber at the transmitter end (sender’s end). At the receiver end, the light is converted back to electricity and then to sound. It is simple as this:


An optical fiber does not carry sound energy directly. Optical fiber is a medium that allows transmission of light signals through it. We can convert sound energy to light and then back to sound energy when it reaches at destination.

Author: Thomas Mathew

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