What property allows light to be guided within the core of an optical fiber?

The property that allows light to be guided within the core of an optical fiber is the refractive index difference between the core and cladding. This difference is essential for the principle of total internal reflection, which is the fundamental mechanism enabling light to be transmitted through the fiber.

In an optical fiber, the core has a higher refractive index than the cladding surrounding it. When light traveling within the core reaches the boundary between the core and the cladding, it encounters a medium with a lower refractive index. If the angle of incidence is greater than a certain critical angle, all of the light is reflected back into the core rather than refracted into the cladding. This phenomenon allows the light to be confined and guided along the length of the fiber, effectively minimizing losses and enabling long-distance transmission.

While other properties like density and surface smoothness may influence the overall performance and efficiency of fiber optics, they are not the main factors responsible for the light-gathering capability within the core itself. The critical aspect is indeed the refractive index difference that facilitates total internal reflection, making the guiding of light possible within the optical fiber.