What principle allows energy to be confined in a fiber optic transmission?

The principle that allows energy to be confined in a fiber optic transmission is total internal reflection. This phenomenon occurs when light traveling within a medium, such as glass or plastic, encounters a boundary with a less dense medium (like air) at an angle greater than a specific threshold, known as the critical angle. Under these conditions, rather than passing through the boundary, the light is reflected back into the denser medium.

In fiber optics, the core of the fiber has a higher refractive index than the cladding that surrounds it. This structure ensures that light signals, once injected into the fiber, will strike the boundary at angles greater than the critical angle, resulting in continuous reflection within the core. This allows light to travel long distances with minimal loss, enabling efficient data transmission over fiber optic networks.

While critical angle is related to the outcome of total internal reflection, it is not the principle itself that facilitates confinement. Light diffraction and refractive index variation have roles in optics, but they do not provide the mechanism for confining light within the fiber.