What distinguishes "fusion splicing" from "mechanical splicing"?

Fusion splicing is distinguished from mechanical splicing primarily by the method of joining the fibers. In fusion splicing, the two fiber ends are aligned and then fused together using heat. This process creates a continuous, permanent connection by melting the glass of the fibers and allowing them to bond at a molecular level as they cool. This results in a lower splice loss and better performance because the refractive index is uniform across the splice, minimizing signal loss and reflection.

In contrast, mechanical splicing involves aligning the fiber ends in a matching fixture and joining them physically, often using an index-matching gel or adhesive. While mechanical splicing provides a useful method to connect fibers, it typically has higher splice loss compared to fusion splicing, primarily due to the air gap and less-than-perfect alignment.

Understanding this fundamental difference helps clarify why fusion splicing is often preferred for permanent installations where signal integrity is crucial, while mechanical splicing may be used for temporary or emergency repairs.