In optical fiber light transmissions, total internal reflection occurs at which interface?

Total internal reflection is a critical phenomenon in optical fibers that allows light to be transmitted with minimal loss. This occurs specifically at the core to cladding interface.

In an optical fiber, the core is made of a material with a higher refractive index than that of the cladding surrounding it. When light traveling through the core reaches the boundary between the core and the cladding at a steep angle, it reflects entirely back into the core instead of refracting into the cladding. This reflection occurs because the angle of incidence exceeds the critical angle, which is determined by the refractive indices of the two materials.

This mechanism is essential for the function of fiber optics, as it ensures that light signals remain contained within the core, enabling long-distance transmission with minimal signal degradation. Other interfaces mentioned do not facilitate total internal reflection the same way, as they either involve transmission to a medium with a lower refractive index or do not connect optical to optical materials, thus not fulfilling the conditions necessary for total internal reflection.