What happens to light when the angle of incidence exceeds the critical angle in an optical fiber?

When the angle of incidence exceeds the critical angle in an optical fiber, total internal reflection occurs. This phenomenon is a key principle in fiber optics. When light traveling from a denser medium (the core of the fiber) to a less dense medium (the cladding) hits the boundary at an angle greater than the critical angle, it cannot pass through the boundary and instead reflects entirely within the core.

In this context, while it may seem intuitive to think that exceeding the critical angle would result in light escaping, the reality is that all light that meets this condition is reflected back into the core rather than escaping or being absorbed. Therefore, the aspect of light escaping does not occur when the angle of incidence exceeds the critical angle; rather, it is contained within the fiber due to this reflection.

Thus, recognizing that exceeding the critical angle results in total internal reflection clarifies that the behavior of light in this scenario does not align with the suggestion of all light escaping.