When fusion splices fail, they typically fail near to, but NOT at, the _____.

The typical failure of fusion splices occurring near the splice boundary relates to how the fibers are joined during the splicing process. In a well-executed fusion splice, the two optical fibers are melted together to form a continuous waveguide for light transmission. However, the splice boundary—the area where the two fibers meet but have not completely become one—can often be the point of stress concentration.

This region is under mechanical stress due to the differing characteristics of the fibers involved, such as core size, refractive index, or even slight misalignments. These variations can lead to microbending or other forms of mechanical failure. As a result, while the splice itself may be intact, the integrity of the connection can be compromised close to this boundary, making it a critical area for potential failure.

In contrast, if the failure were to occur at the end points or the fused area itself, it would indicate a more significant issue with the splice process or the fibers involved. Connectorized ends typically have their own set of failure mechanisms that are not as closely related to the fusion splicing technique itself.