Which phenomenon is essential for the operation of optical fibers?

The operation of optical fibers fundamentally relies on the phenomenon of total internal reflection. This occurs when light travels from a medium with a higher refractive index (such as the core of the optical fiber) to a medium with a lower refractive index (like the cladding surrounding the core) at a certain angle, known as the critical angle. When the light hits the boundary at this angle or more steeply, it is completely reflected back into the core rather than refracted into the cladding. This principle allows light to be confined within the fiber, enabling efficient transmission of data over long distances with minimal loss.

While reflection and refraction are relevant concepts in optics, only total internal reflection permits the light to be trapped within the fiber effectively. Diffraction, on the other hand, deals with the bending of light around obstacles and is not a primary mechanism utilized in the functioning of optical fibers. Therefore, total internal reflection is crucial in ensuring that the light signal travels through the fiber without significant loss, which is essential for the efficiency of optical communication systems.