Mode-field mismatch and alignment mechanisms cause loss when splicing, though it is possible to encourage diffusion across the join to reduce loss. This has the effect of negating Fresnel reflection losses and reduces mode-field mismatch because the guidance properties across the join change more gently, rather than the abrupt step that connectors have. Many splice machines operate by core-alignment, so naturally this minimizes core-misalignment losses. However, if the core is non-concentric with the cladding, surface tension in the fused glass will tend to pull the cladding into alignment instead and could disrupt the core alignment. All Fibercore fibers are designed to minimize core misallignment by optimizing core concentricity.