Where in a fiber-optic network would you expect Fresnel reflections to occur?

Fresnel reflections occur at interfaces where there is a change in the optical medium, which affects the speed of light traveling through the materials. In a fiber-optic network, this primarily happens at connections and mechanical splices. When the signal enters or exits the fiber, it moves from one optical medium (fiber material) to another (air or different types of connectors), resulting in partial reflection of the light signal due to the difference in refractive indices.

This phenomenon can lead to signal loss or reduced signal quality, as some of the light energy reflects back instead of continuing through the intended path. Proper termination techniques and equipment, such as angled connectors, can help minimize these reflections, but the potential for Fresnel reflections remains a critical consideration at these interface points within fiber-optic installations.

In contrast, the other choices are not locations where Fresnel reflections would occur. The core of the fiber is designed for optimal light transmission and does not involve such transitions. The protective coating serves to shield the fiber but does not cause interface reflections under normal operation. Fiber optic amplifiers, while they may interact with light signals, do not create the kind of interface where Fresnel reflections are typically a concern in the same way as at connections and splices.