Fiber optic adapters, also known as couplers, play a crucial role in fiber optic networks by providing a connection point between two fiber optic connectors. The device allows the transmission of light waves through multiple paths. A fiber optic coupler is an essential fiber optic device. It functions by dividing a single incoming light path into multiple outgoing paths, or by combining light from several input paths into a single output fiber. In this tutorial. To this end, one needs splices, plugs, couplers, and switches as well as multiplexers and demultiplexers.