Quick answer: Industry acceptance threshold for a single fusion splice is 0. 1 dB should be. If instead you get them to 0. 02dB (a pretty good splice) each, it's only 0. 2dB for the splices - equivalent to just another km of cable. Figure 1: Primary loss factors in fiber splicing: (A) Mode Field Diameter mismatch, (B) Lateral core offset, and (C) Angular misalignment. Extrinsic Loss (Lateral Offset) 3. Extrinsic Loss (Angular Tilt) Understanding the Variables: w 1, w 2 Mode Field. Typical splice loss values (the measure of loss in optical power across the splice point) are usually lower for fusion splices (typically less than 0. Optical fiber splicing is a critical. Fiber transmission lines will frequently have more than 10 splices between terminal points; to estimate the overall line loss, we need a reliable figure for the splice loss to be expected under varying line conditions.