Fiber optic couplers are optical devices that connect three or more fiber ends, dividing one input between two or more outputs, or combining two or more inputs into one output. The device allows the transmission of light waves through multiple paths. 61835/p65 Cite the article: BibTex BibLaTex plain text HTML Link to this. A fiber coupler is a passive optical device that manages the flow of light signals within an optical network. This capability is fundamental. When using fiber optics, one often needs to use fiber couplers for various purposes.