Splicing of multimode fibers is rather uncritical. Here, substantial transition losses are to be expected only when the fiber parameters are not well matched, e. This article explains the principle of fusion splicing, a common method for making permanent low-loss fiber splices by melting and fusing two fiber ends together, typically with an electric arc. 02 dB. A fusion splicer uses a high-temperature ARC (several thousand °C) generated between two electrodes to melt and fuse the glass cores of two optical fibers. ARC calibration is the process of precisely adjusting the discharge intensity and discharge duration.