How is light guided along the core of a fiber?

Light is guided along the core of a fiber due to the principle of total internal reflection, which occurs because of the difference in refractive indexes between the core and the cladding surrounding it. The core, having a higher refractive index, allows light entering at a certain angle to be reflected back into the core rather than passing into the cladding. This process effectively “traps” the light within the core, ensuring that it travels along the length of the fiber.

This principle is fundamental to fiber optics as it allows for efficient transmission of signals over long distances without significant loss. The design of fiber optics relies heavily on this difference in refractive indexes to ensure that light signals can be maintained with minimal dispersion and attenuation.