Which kind of light is used to carry information through optical fibers?

A. fluorescent
B. sodium-vapor light
C. laser

Semiconductor laser lights

The correct answer is C. laser.

To understand why laser light is used to carry information through optical fibers, let's first explore how optical fibers work.

Optical fibers are thin, flexible strands made of a highly transparent material, usually glass or plastic. They are used to transmit light signals over long distances with very little loss of signal quality.

The basic principle behind optical fibers is total internal reflection. When light enters an optical fiber, it undergoes multiple reflections off the inner walls of the fiber, bouncing back and forth. This allows the light to propagate down the length of the fiber by constantly bouncing off the walls.

Now, let's move on to why laser light is used instead of other types of light sources like fluorescent or sodium-vapor light.

Laser stands for "Light Amplification by Stimulated Emission of Radiation." Laser light is different from other types of light because it is coherent, monochromatic, and highly directional.

Coherence means that the light waves are in phase with each other, resulting in a concentrated beam of light. Monochromaticity means that the laser emits light in a very narrow range of wavelengths, creating a pure color. Directionality means that the laser beam is very focused and travels in a straight line.

These properties of laser light make it ideal for carrying information through optical fibers. The coherent and focused nature of laser light allows it to be efficiently coupled into the tiny core of the optical fiber, minimizing loss of signal strength. The monochromatic nature of laser light also helps in eliminating distortion in the transmitted signal.

Furthermore, laser light can be easily modulated or switched on and off rapidly to encode information. By varying the intensity or pulsing the laser light, it is possible to encode data in the form of 0s and 1s, which can be decoded at the receiving end. This modulation technique is known as intensity modulation or amplitude modulation.

In summary, laser light is used to carry information through optical fibers due to its coherence, monochromaticity, directionality, and ease of modulation.