Insertion loss is the signal power loss caused by inserting devices (such as fiber connectors, fiber jumpers, couplers, etc. It can also be referred to. Insertion loss is usually shortened to IL, and the unit of measurement for insertion loss is dBm. Think of it as the “toll” your signal pays every time it hits a junction—too high, and your data crawls instead of flying. CSRAYZER's polarization-maintaining filter or fused coupler series products are used to split inputs from a polarization-maintaining optical fiber according to the. Erbium Doped Fiber Amplifiers (EDFAs), Multiplexers (MUXs), Demultiplexers (DEMUXs), Fiber Channels, Optical Systems, etc all use connectors. Fiber coupling can be accomplished by fusion splicing.