Fresnel reflection loss occurs when there is an air gap between two connecting fibers at which of the following points?

Fresnel reflection loss is a phenomenon that occurs when light passes from one medium to another, such as from a fiber optic cable to air, and then from air to another fiber optic cable. This process leads to some portion of the light being reflected back instead of transmitting through, which results in a loss of signal strength.

When there is an air gap between two connecting fibers, Fresnel reflection loss occurs at both points where light exits the first fiber and where it enters the second fiber. At the exit of the first fiber, the light transitions from the denser glass medium to a less dense air medium, resulting in some of the light being reflected away. Similarly, as the light then enters the second fiber from the air gap, it encounters another boundary between air and glass where further reflection can occur.

These reflections reduce the amount of light that successfully transmits from one fiber to the next, ultimately impacting the overall efficiency of the optical connection. This understanding highlights the importance of minimizing air gaps and ensuring proper alignment between fiber connections to reduce Fresnel reflection losses in practical applications of fiber optics.