Mode field mismatch and alignment mechanisms cause loss when splicing, though it is possible to encourage diffusion across the join to reduce loss. Fiber optic pigtails are used to connect fiber optic cables using fusion or mechanical splicing. What is a mechanical splice? What is a fusion splice? Why splice? Fiber splicing is one way to join two optical fibers together so the light energy from one optical fiber can be transferred to another. This application note discusses the splice loss measurement technique and investigates the extrinsic and intrinsic factors a ecting the splice loss measurements when joining two bare fibre strands. You want low splice loss because signal loss can weaken communication and reliability. Modern fiber optic networks usually keep splice loss. Splice Loss Estimation and Fiber Imaging Among the optical characteristics of a fusion splice, the splice loss is typically the most important.